Renal & Urology — MCQs

Q: A 65-year-old man presents with painless hematuria. Cystoscopy shows a bladder tumor. Histology confirms transitional cell carcinoma. What is the most important risk factor for this condition?

Smoking. ***Smoking***- **Smoking** is by far the most significant and prevalent risk factor for urothelial (transitional cell) carcinoma, contributing to approximately 50-70% of all cases.- Tobacco smoke contains **aromatic amines** and other carcinogens that are metabolized, excreted in urine, and concentrate in the bladder, leading to **DNA damage** and tumor formation.*Alcohol consumption*- Alcohol consumption is not considered a primary or independent risk factor specifically for **urothelial carcinoma**.- While excessive alcohol intake is linked to other cancers, its direct association with bladder cancer is not robust.*High-fat diet*- High-fat diets are generally associated with an increased risk of certain cancers, such as **colorectal** and **prostate** cancer.- However, dietary factors do not represent the primary pathogenic mechanism for transitional cell carcinoma, which is predominantly driven by urinary carcinogens.*Sedentary lifestyle*- A sedentary lifestyle is a generalized risk factor for several cancers, particularly those linked to **obesity** and metabolic syndromes (e.g., endometrial, breast).- There is no strong, direct, or specific mechanistic link between a sedentary lifestyle and the development of **urothelial carcinoma** compared to chemical exposures.*Family history*- While a small proportion of bladder cancers may show some familial clustering, **environmental exposures** like smoking and occupational chemicals are the overwhelming etiologic factors.- Familial predisposition is a minor risk factor and is considerably less important than direct carcinogenic exposure from **smoking**.

Q: A 71-year-old woman with type 2 diabetes and hypertension is admitted with sepsis secondary to pneumonia. On admission, her creatinine is 156 μmol/L (baseline 98 μmol/L two months ago). She is treated with IV fluids and antibiotics. On day 3, her creatinine rises to 298 μmol/L. Urinalysis shows: protein 2+, blood negative, leucocytes negative. Urine microscopy reveals muddy brown casts. Renal ultrasound shows normal-sized kidneys with no obstruction. What is the most likely diagnosis?

Acute tubular necrosis. ***Acute tubular necrosis***- The presence of **muddy brown casts** on urine microscopy is a pathognomonic finding for **acute tubular necrosis (ATN)**, indicating sloughing of renal tubular epithelial cells.- **Sepsis** is a common cause of **intrinsic AKI** through hypotension and inflammatory mediators, leading to ATN that typically does not resolve immediately with fluid resuscitation.*Contrast-induced nephropathy*- This typically presents as an acute rise in creatinine within **24-48 hours** following the administration of radiocontrast media, which is not mentioned in this patient's history.- While it can cause ATN, the clinical context of **sepsis secondary to pneumonia** provides a more direct etiology for the tubular injury.*Acute interstitial nephritis*- Usually triggered by medications (e.g., NSAIDs, antibiotics) and typically presents with **white cell casts**, pyuria, and sometimes a maculopapular rash or **eosinophilia**.- Urinalysis in this case was **negative for leucocytes**, making an inflammatory interstitial process significantly less likely than ATN.*Pre-renal acute kidney injury*- Pre-renal AKI is characterized by a rapid improvement in renal function following **volume resuscitation** and usually features a normal urinary sediment without casts.- The persistent rise in creatinine despite **IV fluids** and the presence of granular/muddy brown casts indicate progression from pre-renal states to **structural tubular damage**.*Atheroembolic renal disease*- This condition typically occurs after **vascular procedures** or catheterization, resulting in cholesterol emboli that cause livedo reticularis and peripheral eosinophilia.- The onset of renal failure is often more subacute compared to the rapid progression seen in **sepsis-induced ATN**, and muddy brown casts are not a characteristic feature.

Q: A 34-year-old previously healthy woman presents with oliguria and peripheral oedema. Blood tests show: creatinine 320 μmol/L (baseline 72 μmol/L two weeks ago), urea 22.4 mmol/L, albumin 28 g/L. Urinalysis shows protein 4+, blood 2+, and no leucocytes or nitrites. Urine protein:creatinine ratio is 520 mg/mmol. Renal biopsy shows crescentic glomerulonephritis. Serology shows: ANCA negative, anti-GBM negative, ANA 1:640 (speckled pattern), anti-dsDNA positive, C3 0.42 g/L (normal 0.75-1.65), C4 0.08 g/L (normal 0.14-0.54). What is the most likely diagnosis?

Lupus nephritis class IV. ***Lupus nephritis class IV*** - The patient presents with **rapidly progressive glomerulonephritis (RPGN)**, significant **proteinuria**, **positive anti-dsDNA**, high-titre **ANA**, and **hypocomplementemia (low C3 and C4)**, which are hallmark features of **Systemic Lupus Erythematosus (SLE)**. - **Class IV (Diffuse Proliferative)** is the most common and severe form of lupus nephritis, frequently manifesting with **crescentic glomerulonephritis** on biopsy and a combined nephritic-nephrotic picture. *Anti-GBM disease (Goodpasture syndrome)* - This diagnosis is excluded by the **negative anti-GBM serology** results in the patient. - While it causes **crescentic GN**, it does not typically present with **hypocomplementemia** or positive **anti-dsDNA** antibodies. *ANCA-associated vasculitis* - The **negative ANCA** results make this diagnosis highly unlikely in this patient. - ANCA vasculitis is characterized as a **pauci-immune** glomerulonephritis and would typically present with **normal complement levels**, not the profound **hypocomplementemia** seen here. *IgA nephropathy with crescents* - While IgA nephropathy can cause crescentic glomerulonephritis, it typically presents with **normal complement levels**. - The presence of **positive anti-dsDNA** and **low C3 and C4** strongly rules out IgA nephropathy, which lacks these specific serological markers. *Post-streptococcal glomerulonephritis* - Post-streptococcal GN usually shows **low C3 with normal C4** (alternative pathway activation), whereas this patient has both low C3 and **low C4**, indicative of classical pathway activation characteristic of **SLE**. - This condition is not associated with **positive anti-dsDNA** or a high-titre **ANA**.

Q: A 56-year-old woman with chronic kidney disease stage 4 (eGFR 20 mL/min/1.73m²) secondary to IgA nephropathy presents for routine review. She reports increasing fatigue. Blood tests show: haemoglobin 95 g/L, ferritin 280 μg/L, transferrin saturation 28%, PTH 18.5 pmol/L (normal 1.6-6.9), corrected calcium 2.12 mmol/L, phosphate 1.85 mmol/L, 25-hydroxyvitamin D 32 nmol/L. What is the most appropriate initial management of her secondary hyperparathyroidism?

Start colecalciferol 20,000 units weekly. ***Start colecalciferol 20,000 units weekly*** - The initial step in managing **secondary hyperparathyroidism** in CKD is to correct **vitamin D deficiency** (defined as <50 nmol/L); this patient's level is 32 nmol/L. - Replacing **native vitamin D** (colecalciferol) can often lower **PTH levels** significantly before more potent agents are required. *Start alfacalcidol 250 nanograms daily* - **Alfacalcidol** is an active vitamin D analogue typically reserved for when PTH remains high despite normal **25-hydroxyvitamin D** levels. - It carrys a higher risk of **hypercalcaemia** and **hyperphosphataemia** compared to native vitamin D supplementation. *Start calcium carbonate 1.25 g three times daily with meals* - While this patient has mild **hyperphosphataemia**, calcium-based **phosphate binders** are generally secondary to addressing the underlying vitamin D status. - First-line management of moderately elevated phosphate in CKD includes **dietary restriction** and achieving vitamin D sufficiency. *Start cinacalcet 30 mg daily* - **Cinacalcet** is a calcimimetic typically used in **dialysis patients** or those with **refractory hyperparathyroidism**. - It is not indicated as initial therapy when a clear **vitamin D deficiency** is present and untreated. *Arrange parathyroidectomy* - This is a definitive surgical treatment for **tertiary hyperparathyroidism** or severe, symptomatic **refractory secondary hyperparathyroidism**. - It is indicated if PTH is extremely high (often >85 pmol/L) and unresponsive to **medical management**.

A 29-year-old woman at 32 weeks gestation presents to the obstetric assessment unit with headache and right upper quadrant pain. She has no significant past medical history. Blood pressure is 168/112 mmHg. Blood tests show: haemoglobin 102 g/L, platelets 88 × 10^9/L, ALT 245 U/L, AST 312 U/L, bilirubin 34 μmol/L, creatinine 145 μmol/L (booking creatinine was 68 μmol/L), LDH 680 U/L. Urinalysis shows protein 3+. Peripheral blood film shows schistocytes. What is the most appropriate immediate management?

A 38-year-old man with chronic kidney disease stage 5 (eGFR 10 mL/min/1.73m²) secondary to focal segmental glomerulosclerosis is being prepared for renal replacement therapy. He has preserved urine output of approximately 1500 mL per day. He works full-time as a teacher and wishes to minimize time spent on dialysis. Blood tests show: haemoglobin 108 g/L, potassium 5.1 mmol/L, phosphate 1.72 mmol/L, albumin 36 g/L. He has good manual dexterity and lives with his partner. Which renal replacement modality would be most appropriate to offer first?

A 71-year-old woman with type 2 diabetes and hypertension is admitted with sepsis secondary to pneumonia. On admission, her creatinine is 156 μmol/L (baseline 98 μmol/L two months ago). She is treated with IV fluids and antibiotics. On day 3, her creatinine rises to 298 μmol/L. Urinalysis shows: protein 2+, blood negative, leucocytes negative. Urine microscopy reveals muddy brown casts. Renal ultrasound shows normal-sized kidneys with no obstruction. What is the most likely diagnosis?

A 48-year-old woman with no significant past medical history presents to the emergency department with a 6-hour history of severe right loin pain. CT KUB confirms a 5 mm stone at the right pelviureteric junction with mild hydronephrosis. She is afebrile. Blood tests show: white cells 9.2 × 10^9/L, CRP 8 mg/L, creatinine 78 μmol/L. Urinalysis shows blood 3+, leucocytes 1+, nitrites negative. She has been given adequate analgesia with diclofenac and morphine. What is the most appropriate next step in her management?

A 52-year-old woman presents to the emergency department with confusion and agitation. Her husband reports she has had watery diarrhoea for 5 days. She has a history of bipolar disorder treated with lithium for 15 years. Blood tests show: sodium 128 mmol/L, potassium 3.2 mmol/L, creatinine 245 μmol/L (baseline 85 μmol/L), lithium level 2.8 mmol/L (therapeutic range 0.6-1.0). ECG shows sinus tachycardia at 105 bpm. What is the most appropriate immediate management?

A 67-year-old man with chronic kidney disease stage 3a (eGFR 52 mL/min/1.73m²) secondary to diabetic nephropathy attends for annual review. He takes metformin, gliclazide, ramipril, atorvastatin, and aspirin. Blood tests show: HbA1c 64 mmol/mol, creatinine 128 μmol/L (stable from previous), potassium 5.4 mmol/L, bicarbonate 19 mmol/L. Urine albumin:creatinine ratio is 45 mg/mmol. Blood pressure is 138/82 mmHg. What is the most appropriate modification to his management?

A 34-year-old previously healthy woman presents with oliguria and peripheral oedema. Blood tests show: creatinine 320 μmol/L (baseline 72 μmol/L two weeks ago), urea 22.4 mmol/L, albumin 28 g/L. Urinalysis shows protein 4+, blood 2+, and no leucocytes or nitrites. Urine protein:creatinine ratio is 520 mg/mmol. Renal biopsy shows crescentic glomerulonephritis. Serology shows: ANCA negative, anti-GBM negative, ANA 1:640 (speckled pattern), anti-dsDNA positive, C3 0.42 g/L (normal 0.75-1.65), C4 0.08 g/L (normal 0.14-0.54). What is the most likely diagnosis?

A 56-year-old woman with chronic kidney disease stage 4 (eGFR 20 mL/min/1.73m²) secondary to IgA nephropathy presents for routine review. She reports increasing fatigue. Blood tests show: haemoglobin 95 g/L, ferritin 280 μg/L, transferrin saturation 28%, PTH 18.5 pmol/L (normal 1.6-6.9), corrected calcium 2.12 mmol/L, phosphate 1.85 mmol/L, 25-hydroxyvitamin D 32 nmol/L. What is the most appropriate initial management of her secondary hyperparathyroidism?

Q10

A 28-year-old man presents to the emergency department with sudden onset severe left-sided loin pain radiating to the groin. He has vomited twice and appears distressed. He has a history of inflammatory bowel disease (Crohn's disease) and has undergone two small bowel resections. CT KUB shows a 7 mm calculus at the left vesicoureteric junction with moderate hydronephrosis. Blood tests show: creatinine 88 μmol/L, calcium 2.35 mmol/L, uric acid 380 μmol/L. What is the most likely stone composition in this patient?

Renal & Urology UK Medical PG Practice Questions and MCQs

Question 1: A 65-year-old man presents with painless hematuria. Cystoscopy shows a bladder tumor. Histology confirms transitional cell carcinoma. What is the most important risk factor for this condition?

A. Alcohol consumption
B. Smoking (Correct Answer)
C. High-fat diet
D. Sedentary lifestyle
E. Family history

Explanation: ***Smoking***- **Smoking** is by far the most significant and prevalent risk factor for urothelial (transitional cell) carcinoma, contributing to approximately 50-70% of all cases.- Tobacco smoke contains **aromatic amines** and other carcinogens that are metabolized, excreted in urine, and concentrate in the bladder, leading to **DNA damage** and tumor formation.*Alcohol consumption*- Alcohol consumption is not considered a primary or independent risk factor specifically for **urothelial carcinoma**.- While excessive alcohol intake is linked to other cancers, its direct association with bladder cancer is not robust.*High-fat diet*- High-fat diets are generally associated with an increased risk of certain cancers, such as **colorectal** and **prostate** cancer.- However, dietary factors do not represent the primary pathogenic mechanism for transitional cell carcinoma, which is predominantly driven by urinary carcinogens.*Sedentary lifestyle*- A sedentary lifestyle is a generalized risk factor for several cancers, particularly those linked to **obesity** and metabolic syndromes (e.g., endometrial, breast).- There is no strong, direct, or specific mechanistic link between a sedentary lifestyle and the development of **urothelial carcinoma** compared to chemical exposures.*Family history*- While a small proportion of bladder cancers may show some familial clustering, **environmental exposures** like smoking and occupational chemicals are the overwhelming etiologic factors.- Familial predisposition is a minor risk factor and is considerably less important than direct carcinogenic exposure from **smoking**.

Question 2: A 29-year-old woman at 32 weeks gestation presents to the obstetric assessment unit with headache and right upper quadrant pain. She has no significant past medical history. Blood pressure is 168/112 mmHg. Blood tests show: haemoglobin 102 g/L, platelets 88 × 10^9/L, ALT 245 U/L, AST 312 U/L, bilirubin 34 μmol/L, creatinine 145 μmol/L (booking creatinine was 68 μmol/L), LDH 680 U/L. Urinalysis shows protein 3+. Peripheral blood film shows schistocytes. What is the most appropriate immediate management?

A. Commence IV magnesium sulphate and plan delivery within 24-48 hours
B. Commence IV labetalol, IV magnesium sulphate, and arrange immediate delivery (Correct Answer)
C. Commence plasma exchange for thrombotic thrombocytopenic purpura
D. Commence high-dose corticosteroids for HELLP syndrome
E. Transfuse platelets and arrange delivery once platelets >100 × 10^9/L

Explanation: ***Commence IV labetalol, IV magnesium sulphate, and arrange immediate delivery*** - The patient's presentation with headache, right upper quadrant pain, severe hypertension (168/112 mmHg), proteinuria, thrombocytopenia (platelets 88 × 10^9/L), elevated liver enzymes (ALT 245 U/L, AST 312 U/L), elevated LDH, elevated bilirubin, and **schistocytes** on peripheral blood film is highly indicative of **HELLP syndrome** (Hemolysis, Elevated Liver enzymes, Low Platelets) with severe pre-eclampsia and acute kidney injury. - **Immediate delivery** is the definitive and most appropriate management for HELLP syndrome, especially given the severity and multi-organ involvement. **IV labetalol** is crucial for managing severe hypertension to prevent maternal stroke, and **IV magnesium sulphate** is essential for seizure prophylaxis in severe pre-eclampsia/HELLP. *Commence IV magnesium sulphate and plan delivery within 24-48 hours* - While **magnesium sulphate** is correctly indicated for seizure prophylaxis, delaying delivery for **24-48 hours** in the context of established HELLP syndrome with signs of organ dysfunction (AKI, severe liver dysfunction) is dangerous and can lead to severe maternal and fetal complications, including liver rupture, renal failure, or stroke. - The critical nature of **HELLP syndrome** often requires delivery within hours of diagnosis and maternal stabilization, not prolonged expectant management. *Commence plasma exchange for thrombotic thrombocytopenic purpura* - Although both **TTP** and HELLP syndrome can present with microangiopathic hemolytic anemia and thrombocytopenia, the presence of severe **hypertension** and significant **proteinuria** in a pregnant woman points strongly towards HELLP syndrome. - Initiating **plasma exchange**, which is the primary treatment for TTP, would be a misdiagnosis and critically delay the definitive treatment for HELLP syndrome, which is delivery, thereby increasing maternal and fetal morbidity and mortality. *Commence high-dose corticosteroids for HELLP syndrome* - While corticosteroids (e.g., dexamethasone) are sometimes used as an adjunct in HELLP syndrome to potentially improve platelet counts and liver enzyme levels, they are **not the definitive treatment** and do not replace the need for prompt delivery. - The primary management for HELLP syndrome focuses on stabilizing the mother and then delivering the fetus and placenta; corticosteroids for maternal benefit are secondary and should not delay the primary intervention, though steroids for fetal lung maturity might be considered if time permits for delivery within 24-48 hours (which is not the case here given the severity). *Transfuse platelets and arrange delivery once platelets >100 × 10^9/L* - **Platelet transfusion** is generally reserved for platelet counts below 20-50 × 10^9/L, active bleeding, or prior to invasive procedures/delivery, rather than as a routine measure for a count of 88 × 10^9/L. - Delaying delivery to achieve an arbitrary platelet count threshold of **>100 × 10^9/L** is inappropriate and unsafe in HELLP syndrome; the platelet count often only improves significantly post-delivery, and such a delay puts the mother at increased risk of complications like intracranial hemorrhage or abruptio placentae.

Question 3: A 38-year-old man with chronic kidney disease stage 5 (eGFR 10 mL/min/1.73m²) secondary to focal segmental glomerulosclerosis is being prepared for renal replacement therapy. He has preserved urine output of approximately 1500 mL per day. He works full-time as a teacher and wishes to minimize time spent on dialysis. Blood tests show: haemoglobin 108 g/L, potassium 5.1 mmol/L, phosphate 1.72 mmol/L, albumin 36 g/L. He has good manual dexterity and lives with his partner. Which renal replacement modality would be most appropriate to offer first?

A. Continuous ambulatory peritoneal dialysis (CAPD)
B. Automated peritoneal dialysis (APD) (Correct Answer)
C. In-centre haemodialysis three times weekly
D. Home haemodialysis
E. Pre-emptive renal transplantation

Explanation: ***Automated peritoneal dialysis (APD)*** - **APD** is ideal for a full-time teacher as it allows for **overnight dialysis cycles** while the patient sleeps, freeing up their entire day for work and other activities. - The patient's **preserved residual urine output** (1500 mL/day) and **good manual dexterity** are strong indicators for successful home-based peritoneal dialysis, minimizing the impact on lifestyle. *Continuous ambulatory peritoneal dialysis (CAPD)* - **CAPD** requires several **manual exchanges** throughout the day, which would significantly interrupt a teacher's workday and classroom responsibilities. - Although home-based, it offers less **lifestyle flexibility** and independence during waking hours compared to automated peritoneal dialysis. *In-centre haemodialysis three times weekly* - This option involves regular trips to a clinic for **4-hour sessions** three times a week, directly conflicting with the patient's desire to **minimize time spent on dialysis** and maintain full-time employment. - **In-centre haemodialysis** is generally associated with a more rapid decline in **residual renal function** compared to peritoneal dialysis. *Home haemodialysis* - **Home haemodialysis** is a more complex and technically demanding modality, requiring **vascular access** (e.g., AV fistula) and extensive patient training, which could delay the initiation of therapy. - It involves greater equipment setup and ongoing maintenance at home, which can be more **invasive and disruptive** to the patient's living environment than peritoneal dialysis. *Pre-emptive renal transplantation* - While **pre-emptive renal transplantation** is the preferred long-term treatment for CKD stage 5, it is contingent on **donor availability** and is not a dialysis modality to be offered as the initial RRT choice. - The question specifically asks for an appropriate **renal replacement modality** (dialysis) to offer *first* as the patient prepares for RRT.

Question 4: A 71-year-old woman with type 2 diabetes and hypertension is admitted with sepsis secondary to pneumonia. On admission, her creatinine is 156 μmol/L (baseline 98 μmol/L two months ago). She is treated with IV fluids and antibiotics. On day 3, her creatinine rises to 298 μmol/L. Urinalysis shows: protein 2+, blood negative, leucocytes negative. Urine microscopy reveals muddy brown casts. Renal ultrasound shows normal-sized kidneys with no obstruction. What is the most likely diagnosis?

A. Acute tubular necrosis (Correct Answer)
B. Contrast-induced nephropathy
C. Acute interstitial nephritis
D. Pre-renal acute kidney injury
E. Atheroembolic renal disease

Explanation: ***Acute tubular necrosis***- The presence of **muddy brown casts** on urine microscopy is a pathognomonic finding for **acute tubular necrosis (ATN)**, indicating sloughing of renal tubular epithelial cells.- **Sepsis** is a common cause of **intrinsic AKI** through hypotension and inflammatory mediators, leading to ATN that typically does not resolve immediately with fluid resuscitation.*Contrast-induced nephropathy*- This typically presents as an acute rise in creatinine within **24-48 hours** following the administration of radiocontrast media, which is not mentioned in this patient's history.- While it can cause ATN, the clinical context of **sepsis secondary to pneumonia** provides a more direct etiology for the tubular injury.*Acute interstitial nephritis*- Usually triggered by medications (e.g., NSAIDs, antibiotics) and typically presents with **white cell casts**, pyuria, and sometimes a maculopapular rash or **eosinophilia**.- Urinalysis in this case was **negative for leucocytes**, making an inflammatory interstitial process significantly less likely than ATN.*Pre-renal acute kidney injury*- Pre-renal AKI is characterized by a rapid improvement in renal function following **volume resuscitation** and usually features a normal urinary sediment without casts.- The persistent rise in creatinine despite **IV fluids** and the presence of granular/muddy brown casts indicate progression from pre-renal states to **structural tubular damage**.*Atheroembolic renal disease*- This condition typically occurs after **vascular procedures** or catheterization, resulting in cholesterol emboli that cause livedo reticularis and peripheral eosinophilia.- The onset of renal failure is often more subacute compared to the rapid progression seen in **sepsis-induced ATN**, and muddy brown casts are not a characteristic feature.

Question 5: A 48-year-old woman with no significant past medical history presents to the emergency department with a 6-hour history of severe right loin pain. CT KUB confirms a 5 mm stone at the right pelviureteric junction with mild hydronephrosis. She is afebrile. Blood tests show: white cells 9.2 × 10^9/L, CRP 8 mg/L, creatinine 78 μmol/L. Urinalysis shows blood 3+, leucocytes 1+, nitrites negative. She has been given adequate analgesia with diclofenac and morphine. What is the most appropriate next step in her management?

A. Discharge with analgesia, alpha-blocker, and follow-up in stone clinic (Correct Answer)
B. Admit for IV antibiotics due to obstructive pyelonephritis
C. Arrange urgent ureteroscopy and stone extraction within 48 hours
D. Insert percutaneous nephrostomy for decompression
E. Arrange extracorporeal shock wave lithotripsy (ESWL) within one week

Explanation: ***Discharge with analgesia, alpha-blocker, and follow-up in stone clinic*** - This patient presents with **uncomplicated renal colic** as evidenced by the 5 mm stone, controlled pain, normal inflammatory markers, and absence of fever or signs of infection (afebrile, negative nitrites). - Stones **less than 10 mm** (especially 5 mm) have a high rate of spontaneous passage, and **medical expulsive therapy (MET)** with an alpha-blocker like tamsulosin is recommended to facilitate this process. *Admit for IV antibiotics due to obstructive pyelonephritis* - There is no evidence of infection; the patient is **afebrile**, and **blood tests** (WBC 9.2, CRP 8) do not indicate significant systemic inflammation. - **Obstructive pyelonephritis** is a medical emergency characterized by fever, flank pain, and signs of infection with obstruction, which are absent here. *Arrange urgent ureteroscopy and stone extraction within 48 hours* - Urgent invasive procedures like **ureteroscopy** are typically reserved for patients with **intractable pain**, signs of infection, acute kidney injury, or stones unlikely to pass spontaneously (e.g., larger stones). - Given the small size of the stone (5 mm) and controlled pain, a trial of conservative management is more appropriate before considering invasive intervention. *Insert percutaneous nephrostomy for decompression* - **Percutaneous nephrostomy** is an invasive procedure indicated for urgent drainage of an **infected obstructed kidney**, severe hydronephrosis with renal impairment, or in patients with a solitary kidney. - The patient has only **mild hydronephrosis** and no signs of infection or acute kidney injury, thus immediate decompression is not warranted. *Arrange extracorporeal shock wave lithotripsy (ESWL) within one week* - **ESWL** is an appropriate treatment for certain stone types and sizes, but for a small 5 mm stone, the chance of **spontaneous passage** with MET is high, making it the preferred initial approach. - Proceeding directly to ESWL for a small, uncomplicated stone bypasses less invasive and potentially successful conservative management, incurring unnecessary costs and risks.

Question 6: A 52-year-old woman presents to the emergency department with confusion and agitation. Her husband reports she has had watery diarrhoea for 5 days. She has a history of bipolar disorder treated with lithium for 15 years. Blood tests show: sodium 128 mmol/L, potassium 3.2 mmol/L, creatinine 245 μmol/L (baseline 85 μmol/L), lithium level 2.8 mmol/L (therapeutic range 0.6-1.0). ECG shows sinus tachycardia at 105 bpm. What is the most appropriate immediate management?

A. Stop lithium, give IV 0.9% saline, and arrange urgent haemodialysis (Correct Answer)
B. Stop lithium, give IV 0.9% saline, and recheck lithium level in 12 hours
C. Continue lithium, correct dehydration, and arrange gastroenterology review
D. Stop lithium, give hypertonic saline for hyponatraemia, then arrange dialysis
E. Stop lithium, give IV fluids, and start haemofiltration

Explanation: ***Stop lithium, give IV 0.9% saline, and arrange urgent haemodialysis***- The patient presents with **severe lithium toxicity** (level 2.8 mmol/L) complicated by **Acute Kidney Injury (AKI)** and neurological symptoms like confusion and agitation.- **Haemodialysis** is indicated when lithium levels exceed 2.5 mmol/L in the presence of renal impairment or severe clinical toxicity, as it is the most efficient method for rapid clearance.*Stop lithium, give IV 0.9% saline, and recheck lithium level in 12 hours*- Waiting 12 hours to recheck levels is dangerous in a patient with **neurological symptoms** and **renal impairment**, as toxicity can be life-threatening.- While **IV normal saline** helps correct hypovolaemic hyponatraemia and promotes renal lithium excretion, it is insufficient as monotherapy for severe toxicity.*Continue lithium, correct dehydration, and arrange gastroenterology review*- **Lithium** must be stopped immediately; continuing it would worsen the toxic accumulation and risk permanent **neurotoxicity** or cardiac arrest.- Focusing on a gastroenterology review ignores the acute medical emergency of **lithium-induced encephalopathy** and renal failure.*Stop lithium, give hypertonic saline for hyponatraemia, then arrange dialysis*- **Hypertonic saline** is generally reserved for severe, symptomatic hyponatraemia with risk of cerebral oedema, whereas this patient’s sodium level will likely correct with **volume resuscitation**.- Delaying dialysis to manage mild-to-moderate hyponatraemia first is inappropriate when the primary threat is the high **lithium concentration**.*Stop lithium, give IV fluids, and start haemofiltration*- **Haemofiltration** is significantly less effective than **haemodialysis** for removing lithium because lithium is a small ion that is best cleared via diffusion.- Rapid clearance of high lithium levels in an emergency setting is the standard of care, making **intermittent haemodialysis** the preferred modality.

Question 7: A 67-year-old man with chronic kidney disease stage 3a (eGFR 52 mL/min/1.73m²) secondary to diabetic nephropathy attends for annual review. He takes metformin, gliclazide, ramipril, atorvastatin, and aspirin. Blood tests show: HbA1c 64 mmol/mol, creatinine 128 μmol/L (stable from previous), potassium 5.4 mmol/L, bicarbonate 19 mmol/L. Urine albumin:creatinine ratio is 45 mg/mmol. Blood pressure is 138/82 mmHg. What is the most appropriate modification to his management?

A. Add SGLT2 inhibitor for renoprotection (Correct Answer)
B. Increase ramipril dose to maximize renoprotection
C. Stop ramipril due to hyperkalaemia and worsening renal function
D. Add sodium bicarbonate supplementation for metabolic acidosis
E. Add spironolactone for additional proteinuria reduction

Explanation: ***Add SGLT2 inhibitor for renoprotection*** - **SGLT2 inhibitors** are a cornerstone in managing **diabetic kidney disease** with albuminuria, significantly reducing the risk of **CKD progression** and cardiovascular events, independent of glycemic control. - The patient's **eGFR (52 mL/min/1.73m²)** and **uACR (45 mg/mmol)** make him an ideal candidate for initiation, offering substantial **renoprotective benefits** with a favorable safety profile regarding potassium. *Increase ramipril dose to maximize renoprotection* - The patient already presents with **borderline hyperkalemia (5.4 mmol/L)**; increasing the dose of an **ACE inhibitor** would significantly elevate the risk of developing **clinically significant hyperkalemia**. - While ACE inhibitors are vital, the current blood pressure is near target, and the addition of an **SGLT2 inhibitor** provides a safer and more evidence-based next step for renoprotection in this context. *Stop ramipril due to hyperkalaemia and worsening renal function* - The **creatinine is stable** from previous readings, indicating no acute worsening of renal function, and a potassium of 5.4 mmol/L is manageable, not warranting immediate cessation of **renoprotective therapy**. - Stopping the ACE inhibitor would eliminate a critical component of **renoprotection** against **proteinuric progression** in diabetic nephropathy, which is generally not recommended unless severe adverse effects occur. *Add sodium bicarbonate supplementation for metabolic acidosis* - NICE guidelines typically suggest considering **sodium bicarbonate** supplementation when serum bicarbonate levels are **less than 18 mmol/L**; this patient's level is 19 mmol/L. - While metabolic acidosis should be monitored, it is not the most urgent or impactful intervention for slowing the **underlying progression of CKD** and reducing cardiovascular risk compared to adding an SGLT2 inhibitor. *Add spironolactone for additional proteinuria reduction* - Adding a **mineralocorticoid receptor antagonist (MRA)** like spironolactone to an ACE inhibitor in a patient with an **eGFR of 52 mL/min/1.73m²** and a **potassium of 5.4 mmol/L** carries a very high risk of inducing **severe hyperkalemia**. - Although MRAs can reduce proteinuria, **SGLT2 inhibitors** offer superior evidence for long-term **renal outcomes** and a more favorable potassium safety profile in patients with CKD and diabetes.

Question 8: A 34-year-old previously healthy woman presents with oliguria and peripheral oedema. Blood tests show: creatinine 320 μmol/L (baseline 72 μmol/L two weeks ago), urea 22.4 mmol/L, albumin 28 g/L. Urinalysis shows protein 4+, blood 2+, and no leucocytes or nitrites. Urine protein:creatinine ratio is 520 mg/mmol. Renal biopsy shows crescentic glomerulonephritis. Serology shows: ANCA negative, anti-GBM negative, ANA 1:640 (speckled pattern), anti-dsDNA positive, C3 0.42 g/L (normal 0.75-1.65), C4 0.08 g/L (normal 0.14-0.54). What is the most likely diagnosis?

A. Lupus nephritis class IV (Correct Answer)
B. Anti-GBM disease (Goodpasture syndrome)
C. ANCA-associated vasculitis
D. IgA nephropathy with crescents
E. Post-streptococcal glomerulonephritis

Explanation: ***Lupus nephritis class IV*** - The patient presents with **rapidly progressive glomerulonephritis (RPGN)**, significant **proteinuria**, **positive anti-dsDNA**, high-titre **ANA**, and **hypocomplementemia (low C3 and C4)**, which are hallmark features of **Systemic Lupus Erythematosus (SLE)**. - **Class IV (Diffuse Proliferative)** is the most common and severe form of lupus nephritis, frequently manifesting with **crescentic glomerulonephritis** on biopsy and a combined nephritic-nephrotic picture. *Anti-GBM disease (Goodpasture syndrome)* - This diagnosis is excluded by the **negative anti-GBM serology** results in the patient. - While it causes **crescentic GN**, it does not typically present with **hypocomplementemia** or positive **anti-dsDNA** antibodies. *ANCA-associated vasculitis* - The **negative ANCA** results make this diagnosis highly unlikely in this patient. - ANCA vasculitis is characterized as a **pauci-immune** glomerulonephritis and would typically present with **normal complement levels**, not the profound **hypocomplementemia** seen here. *IgA nephropathy with crescents* - While IgA nephropathy can cause crescentic glomerulonephritis, it typically presents with **normal complement levels**. - The presence of **positive anti-dsDNA** and **low C3 and C4** strongly rules out IgA nephropathy, which lacks these specific serological markers. *Post-streptococcal glomerulonephritis* - Post-streptococcal GN usually shows **low C3 with normal C4** (alternative pathway activation), whereas this patient has both low C3 and **low C4**, indicative of classical pathway activation characteristic of **SLE**. - This condition is not associated with **positive anti-dsDNA** or a high-titre **ANA**.

Question 9: A 56-year-old woman with chronic kidney disease stage 4 (eGFR 20 mL/min/1.73m²) secondary to IgA nephropathy presents for routine review. She reports increasing fatigue. Blood tests show: haemoglobin 95 g/L, ferritin 280 μg/L, transferrin saturation 28%, PTH 18.5 pmol/L (normal 1.6-6.9), corrected calcium 2.12 mmol/L, phosphate 1.85 mmol/L, 25-hydroxyvitamin D 32 nmol/L. What is the most appropriate initial management of her secondary hyperparathyroidism?

A. Start alfacalcidol 250 nanograms daily
B. Start calcium carbonate 1.25 g three times daily with meals
C. Start cinacalcet 30 mg daily
D. Arrange parathyroidectomy
E. Start colecalciferol 20,000 units weekly (Correct Answer)

Explanation: ***Start colecalciferol 20,000 units weekly*** - The initial step in managing **secondary hyperparathyroidism** in CKD is to correct **vitamin D deficiency** (defined as <50 nmol/L); this patient's level is 32 nmol/L. - Replacing **native vitamin D** (colecalciferol) can often lower **PTH levels** significantly before more potent agents are required. *Start alfacalcidol 250 nanograms daily* - **Alfacalcidol** is an active vitamin D analogue typically reserved for when PTH remains high despite normal **25-hydroxyvitamin D** levels. - It carrys a higher risk of **hypercalcaemia** and **hyperphosphataemia** compared to native vitamin D supplementation. *Start calcium carbonate 1.25 g three times daily with meals* - While this patient has mild **hyperphosphataemia**, calcium-based **phosphate binders** are generally secondary to addressing the underlying vitamin D status. - First-line management of moderately elevated phosphate in CKD includes **dietary restriction** and achieving vitamin D sufficiency. *Start cinacalcet 30 mg daily* - **Cinacalcet** is a calcimimetic typically used in **dialysis patients** or those with **refractory hyperparathyroidism**. - It is not indicated as initial therapy when a clear **vitamin D deficiency** is present and untreated. *Arrange parathyroidectomy* - This is a definitive surgical treatment for **tertiary hyperparathyroidism** or severe, symptomatic **refractory secondary hyperparathyroidism**. - It is indicated if PTH is extremely high (often >85 pmol/L) and unresponsive to **medical management**.

Question 10: A 28-year-old man presents to the emergency department with sudden onset severe left-sided loin pain radiating to the groin. He has vomited twice and appears distressed. He has a history of inflammatory bowel disease (Crohn's disease) and has undergone two small bowel resections. CT KUB shows a 7 mm calculus at the left vesicoureteric junction with moderate hydronephrosis. Blood tests show: creatinine 88 μmol/L, calcium 2.35 mmol/L, uric acid 380 μmol/L. What is the most likely stone composition in this patient?

A. Calcium oxalate (Correct Answer)
B. Calcium phosphate
C. Uric acid
D. Struvite (magnesium ammonium phosphate)
E. Cystine

Explanation: ***Calcium oxalate***- In patients with **Crohn's disease** and a history of **small bowel resections**, **fat malabsorption** is common. Unabsorbed fatty acids in the colon bind to calcium, preventing it from binding to oxalate, thus increasing the absorption of **free oxalate** (enteric hyperoxaluria).- This increased systemic oxalate is excreted in the urine, leading to supersaturation and the formation of **calcium oxalate stones**, which are the most common type of kidney stone in this clinical context.*Calcium phosphate*- These stones are typically associated with conditions such as **renal tubular acidosis (Type 1)** or **primary hyperparathyroidism**, neither of which is indicated by the patient's presentation or blood test results.- They usually form in **alkaline urine**, whereas patients with chronic diarrhea from Crohn's may have acidic urine due to bicarbonate loss, making calcium phosphate less likely.*Uric acid*- While chronic diarrhea can lead to concentrated, acidic urine and potentially **uric acid stone formation**, the patient's serum **uric acid level is normal (380 μmol/L)**, which does not support this as the primary etiology.- Uric acid stones are also often **radiolucent** on plain X-ray, though visible on CT, but the direct metabolic consequence of Crohn's disease points more strongly to oxalate.*Struvite (magnesium ammonium phosphate)*- **Struvite stones** are **infection stones**, formed in the presence of **urease-producing bacteria** (e.g., *Proteus*, *Klebsiella*) that hydrolyze urea to ammonia, raising urine pH and promoting stone formation.- They are often associated with **recurrent urinary tract infections** and can grow to form **staghorn calculi**, neither of which is suggested in this patient's presentation.*Cystine*- **Cystine stones** result from **cystinuria**, an **autosomal recessive genetic disorder** affecting the renal tubular reabsorption of dibasic amino acids.- While typically presenting in younger individuals, there is no history or clinical feature to suggest this rare metabolic disorder, such as characteristic **hexagonal crystals** in urine or a family history.

Question 11: A 42-year-old woman presents with a 2-day history of dysuria, urinary frequency, and visible haematuria. She reports similar episodes twice in the past year. She has no fever or loin pain. Urine dipstick shows blood 3+, leucocytes 2+, nitrites positive, protein 1+. Midstream urine culture grows >10^5 colony-forming units/mL of Escherichia coli sensitive to trimethoprim and nitrofurantoin. What is the most appropriate next step in her management after completing antibiotic treatment?

A. Arrange cystoscopy and renal tract ultrasound to investigate for underlying pathology (Correct Answer)
B. Prescribe prophylactic low-dose nitrofurantoin for 6 months
C. Provide patient with standby antibiotics for future episodes
D. Repeat urine culture after treatment to ensure eradication
E. Reassure and discharge with advice on fluid intake and post-coital voiding

Explanation: ***Arrange cystoscopy and renal tract ultrasound to investigate for underlying pathology*** - In a woman aged >40 years, the presence of **visible haematuria** (even during a UTI) necessitates investigation to rule out **urological malignancy** or structural abnormalities. - While **recurrent UTIs** are common, the red-flag symptom of gross haematuria in this age group mandates **cystoscopy** and upper tract imaging per clinical guidelines. *Prescribe prophylactic low-dose nitrofurantoin for 6 months* - **Antibiotic prophylaxis** is a management strategy for recurrent UTIs, but it should only be considered after **underlying pathology** has been excluded via imaging. - Starting prophylaxis prematurely could mask symptoms of a more serious condition like **bladder cancer** or **nephrolithiasis**. *Provide patient with standby antibiotics for future episodes* - **Self-start/Standby antibiotics** are useful for patients with frequent recurrences who can accurately self-diagnose, but this does not address the need for **haematuria investigation**. - This approach is appropriate for symptomatic relief in verified low-risk patients, not as a primary step for a patient needing **red-flag investigations**. *Repeat urine culture after treatment to ensure eradication* - A **test of cure** is not routinely recommended for uncomplicated cystitis if the patient's symptoms have fully resolved. - Focusing on **culture eradication** ignores the more critical clinical requirement to investigate the cause of **visible haematuria** in a 42-year-old. *Reassure and discharge with advice on fluid intake and post-coital voiding* - While **lifestyle modifications** such as hydration and post-coital voiding are helpful for prevention, they are insufficient for a patient with **visible haematuria**. - Discharging the patient without further investigation would be unsafe, as it risks missing a diagnosis of **malignancy** or chronic renal calculi.

Question 12: A 75-year-old man with benign prostatic hyperplasia presents to the emergency department with a 12-hour history of complete inability to pass urine and severe suprapubic pain. Clinical examination reveals a palpable bladder extending to the umbilicus. A urinary catheter is successfully inserted, draining 1200 mL of urine immediately. Over the next 4 hours, he produces a further 2500 mL of urine. Blood tests show: sodium 145 mmol/L, potassium 3.8 mmol/L, creatinine 156 μmol/L (baseline 95 μmol/L). What is the most appropriate immediate management?

A. IV fluid replacement with 0.9% saline at 250 mL/hour
B. Restrict fluids to 1000 mL per 24 hours to prevent fluid overload
C. IV fluid replacement matching urine output plus insensible losses (Correct Answer)
D. Start furosemide 40 mg intravenously to manage polyuria
E. Emergency nephrology referral for urgent haemodialysis

Explanation: ***IV fluid replacement matching urine output plus insensible losses*** - This patient is experiencing **post-obstructive diuresis**, characterized by massive urine output (>200 mL/hr) following the relief of a severe urinary tract obstruction. - Management requires **replacement of fluid losses** (typically half-volume to full-volume matching) to prevent severe **hypovolemia**, hypotension, and potentially fatal electrolyte imbalances during the polyuric phase. *IV fluid replacement with 0.9% saline at 250 mL/hour* - A fixed rate of 250 mL/hour is insufficient for this patient, who has already produced **more than 600 mL/hour** in the last four hours. - Standard fixed rates may lead to a **net fluid deficit** and worsening of the patient's pre-existing **acute kidney injury** (evidenced by the elevated creatinine). *Restrict fluids to 1000 mL per 24 hours to prevent fluid overload* - Fluid restriction is dangerous in this context as the diuresis is a physiological response to **osmotic load** (retained urea/electrolytes) and impaired tubular concentration. - Restricting intake would rapidly lead to **dehydration**, severe **hypernatremia**, and potentially cardiovascular collapse. *Start furosemide 40 mg intravenously to manage polyuria* - Furosemide is a **loop diuretic** that would exacerbate renal losses and worsen the patient's fluid status rather than managing the polyuria. - Diuretics are **contraindicated** here as the polyuria is a result of post-obstructive recovery and not due to primary fluid overload. *Emergency nephrology referral for urgent haemodialysis* - There are no indications for **urgent hemodialysis**, such as refractory hyperkalemia, severe metabolic acidosis, or uremic complications. - The rise in creatinine is likely **pre-renal or post-renal** in nature and should improve with the relief of obstruction and appropriate volume replacement.

Question 13: A 58-year-old woman with rheumatoid arthritis treated with methotrexate and NSAIDs presents with a 3-day history of vomiting and diarrhoea. Her baseline creatinine is 78 μmol/L. Current blood tests show: creatinine 245 μmol/L, urea 18.2 mmol/L, sodium 132 mmol/L, potassium 5.2 mmol/L. Urinalysis shows no protein or blood. Renal ultrasound shows normal-sized kidneys with no hydronephrosis. What is the most likely underlying mechanism of her acute kidney injury?

A. Pre-renal acute kidney injury due to volume depletion (Correct Answer)
B. Acute tubular necrosis secondary to methotrexate toxicity
C. Acute interstitial nephritis from NSAID therapy
D. Obstructive uropathy from methotrexate crystalluria
E. Glomerulonephritis related to rheumatoid arthritis

Explanation: ***Pre-renal acute kidney injury due to volume depletion*** - The patient's 3-day history of **vomiting and diarrhoea** indicates significant **volume depletion**, leading to decreased renal perfusion. This is supported by the marked increase in **creatinine (78 to 245 μmol/L)** and the high **urea-to-creatinine ratio**. - Her use of **NSAIDs** exacerbates pre-renal AKI by inhibiting **prostaglandin synthesis**, which normally causes **afferent arteriolar vasodilation** to maintain renal blood flow, especially in hypovolemic states. *Acute tubular necrosis secondary to methotrexate toxicity* - While methotrexate can cause renal injury, it is typically associated with **high doses** used in oncology, not the lower doses prescribed for **rheumatoid arthritis**. - **Acute tubular necrosis (ATN)** would usually present with **granular casts** or renal tubular epithelial cells on urinalysis, which are not mentioned in this case. *Acute interstitial nephritis from NSAID therapy* - **Acute interstitial nephritis (AIN)** often presents with **eosinophilia**, **pyuria**, or significant **proteinuria**, none of which are reported in the urinalysis. - AIN is an idiosyncratic hypersensitivity reaction, which is less likely given the acute onset following a clear episode of **gastrointestinal fluid loss**. *Obstructive uropathy from methotrexate crystalluria* - The **renal ultrasound** specifically showed **normal-sized kidneys with no hydronephrosis**, effectively ruling out any form of **obstructive uropathy**. - Methotrexate **crystalluria** is also primarily a concern with very high doses and would typically lead to obstruction and associated imaging findings. *Glomerulonephritis related to rheumatoid arthritis* - This diagnosis is highly unlikely because **glomerulonephritis** typically involves **haematuria** and/or **significant proteinuria** on urinalysis, both of which are absent. - The acute presentation following an episode of **vomiting and diarrhoea** is inconsistent with the more chronic or subacute progression of **rheumatoid arthritis-related glomerulonephritis**.

Question 14: A 62-year-old man with chronic kidney disease stage 3b (eGFR 40 mL/min/1.73m²) is being evaluated for worsening renal function. His medication history includes ramipril, atorvastatin, and amlodipine. Blood tests show: haemoglobin 102 g/L, ferritin 450 μg/L, transferrin saturation 18%, serum vitamin B12 320 ng/L, folate 8 μg/L. What is the most appropriate interpretation of these haematological findings?

A. Anaemia of chronic kidney disease with functional iron deficiency (Correct Answer)
B. Iron deficiency anaemia due to gastrointestinal blood loss
C. Combined vitamin B12 and folate deficiency
D. Anaemia secondary to ACE inhibitor therapy
E. Normal variant requiring no intervention

Explanation: ***Anaemia of chronic kidney disease with functional iron deficiency*** - The patient's **haemoglobin of 102 g/L** indicates anaemia, which is common in **CKD stage 3b (eGFR 40 mL/min/1.73m²)** due to reduced **erythropoietin** production by the kidneys. - The **ferritin of 450 μg/L** suggests adequate iron stores, but a **transferrin saturation (TSAT) of 18%** (below the target of >20% in CKD patients) indicates **functional iron deficiency**, where iron is sequestered and not available for erythropoiesis due to inflammation. *Iron deficiency anaemia due to gastrointestinal blood loss* - **Absolute iron deficiency anaemia**, often caused by chronic blood loss (e.g., GI bleeding), is typically characterized by **low ferritin levels** (usually <100 μg/L in CKD patients). - This patient's **ferritin of 450 μg/L** makes absolute iron deficiency unlikely; instead, it points towards sufficient iron stores but impaired utilization due to chronic inflammation. *Combined vitamin B12 and folate deficiency* - The patient's **serum vitamin B12 (320 ng/L)** and **folate (8 μg/L)** levels are within normal limits, ruling out deficiencies in these vitamins as the primary cause of anaemia. - Deficiencies in these vitamins typically lead to **macrocytic anaemia**, whereas anaemia of CKD is usually **normocytic**. *Anaemia secondary to ACE inhibitor therapy* - While **ramipril (an ACE inhibitor)** can occasionally cause a mild reduction in haemoglobin by decreasing erythropoietin production, it is rarely the sole cause of significant anaemia, especially with the observed iron profile. - The combination of **low TSAT** and **high ferritin** strongly suggests functional iron deficiency and anaemia of CKD as the predominant factors, rather than a drug-induced anaemia alone. *Normal variant requiring no intervention* - A **haemoglobin level of 102 g/L** is significantly below the normal range for adult males, indicating true **anaemia** that requires medical attention and intervention, particularly in the context of advanced CKD. - Anaemia in CKD is a serious condition that contributes to patient morbidity and mortality and necessitates management, typically with iron supplementation and potentially erythropoiesis-stimulating agents.

Question 15: A 45-year-old woman presents to the emergency department with severe muscle weakness and palpitations. She has a history of hypertension treated with lisinopril and bendroflumethiazide. ECG shows tall tented T waves and a prolonged PR interval. Blood tests reveal: sodium 138 mmol/L, potassium 7.8 mmol/L, creatinine 95 μmol/L, glucose 5.2 mmol/L. Which medication should be given first to protect against the cardiac effects of hyperkalaemia?

A. 10 units of insulin with 50 mL of 50% glucose intravenously
B. 10 mL of 10% calcium gluconate intravenously (Correct Answer)
C. 15 mg salbutamol nebuliser
D. Sodium polystyrene sulfonate 15 g orally
E. Sodium bicarbonate 50 mmol intravenously

Explanation: ***10 mL of 10% calcium gluconate intravenously*** - This is the **priority intervention** for severe hyperkalaemia with ECG changes (tall tented T waves, prolonged PR interval) because it **stabilizes the myocardial membrane** and reduces the risk of lethal arrhythmias. - It works within **1-3 minutes** by antagonizing the cardiac effects of potassium, effectively "buying time" for more definitive potassium-lowering therapies, though it does not lower the serum potassium level itself. *10 units of insulin with 50 mL of 50% glucose intravenously* - This treatment helps **lower serum potassium** by shifting it into the **intracellular compartment**, but its onset of action is typically slower (15-30 minutes) than calcium gluconate for cardiac protection. - It should be administered as a second step after the heart has been protected with **intravenous calcium** due to its delayed onset for urgent cardioprotection. *15 mg salbutamol nebuliser* - **Beta-2 agonists** like salbutamol stimulate the Na+/K+ ATPase pump to drive potassium into cells, but their onset of action is slower (30-90 minutes) compared to calcium or insulin. - It is used as an **adjunctive therapy** to lower potassium and is not the first-line agent for immediate cardiac membrane stabilization in severe hyperkalaemia. *Sodium polystyrene sulfonate 15 g orally* - This is a **cation-exchange resin** that removes potassium from the body via the gastrointestinal tract, but it has a **delayed onset** of several hours. - It is **not suitable for emergency management** of acute, severe hyperkalaemia with ECG changes, as it cannot provide rapid cardioprotection. *Sodium bicarbonate 50 mmol intravenously* - Sodium bicarbonate can shift potassium intracellularly by increasing blood pH, but it is generally reserved for patients with concurrent **metabolic acidosis** and is less effective than calcium for immediate cardiac stabilization. - In this clinical scenario, it is **less potent** and has a slower onset for urgent cardioprotection compared to calcium gluconate.

Question 16: A 47-year-old woman presents with severe nausea and decreased urine output 24 hours after undergoing contrast-enhanced CT pulmonary angiogram for suspected pulmonary embolism. Her background includes type 2 diabetes (HbA1c 76 mmol/mol) and hypertension treated with lisinopril and metformin. Pre-CT creatinine was 142 μmol/L. Current blood tests show: creatinine 287 μmol/L, urea 19.4 mmol/L, potassium 5.2 mmol/L. Urinalysis shows muddy brown casts. Which feature of her presentation would most strongly indicate a need for urgent haemodialysis?

A. Creatinine rise of >100% within 24 hours suggesting severe acute kidney injury
B. Development of pulmonary oedema with oxygen saturation 88% on air despite diuretics (Correct Answer)
C. Persistent metabolic acidosis with pH 7.28 and bicarbonate 16 mmol/L
D. Serum potassium of 5.2 mmol/L with ECG changes of peaked T waves
E. Urea level of 19.4 mmol/L indicating uraemic symptoms

Explanation: ***Development of pulmonary oedema with oxygen saturation 88% on air despite diuretics***- This represents **refractory fluid overload**, a critical component of the **AEIOU mnemonic** for urgent haemodialysis indications.- In the context of **acute kidney injury (AKI)**, hypoxia failing to respond to medical management is a life-threatening emergency requiring immediate renal replacement therapy.*Creatinine rise of >100% within 24 hours suggesting severe acute kidney injury*- While this indicates **AKI Stage 3**, the absolute level or rate of creatinine rise itself is not an independent indication for dialysis without associated clinical complications.- Initial management focuses on **fluid balance**, treating the underlying cause, and monitoring for physiological instability rather than immediate dialysis based solely on creatinine trends.*Persistent metabolic acidosis with pH 7.28 and bicarbonate 16 mmol/L*- Urgent dialysis for **acidosis** is generally reserved for a **pH < 7.20** or cases where medical therapy with bicarbonate is ineffective or contraindicated.- A pH of 7.28 with a bicarbonate of 16 mmol/L indicates a moderate acidosis, which should initially be managed medically and typically does not meet the threshold for **emergent intervention** with dialysis.*Serum potassium of 5.2 mmol/L with ECG changes of peaked T waves*- **Hyperkalaemia** typically mandates urgent dialysis only when levels exceed **6.5 mmol/L** or when severe ECG changes (e.g., wide QRS, ventricular arrhythmias) persist despite medical management (e.g., calcium gluconate, insulin-glucose).- A potassium of 5.2 mmol/L is mildly elevated, and **peaked T waves** at this level would still warrant medical management rather than immediate dialysis.*Urea level of 19.4 mmol/L indicating uraemic symptoms*- **Uraemia** is an indication for dialysis only when it leads to severe clinical complications such as **pericarditis**, **encephalopathy**, overt **uraemic bleeding**, or profound neurological changes.- A urea level of 19.4 mmol/L is elevated but does not automatically mandate dialysis unless these severe **clinical manifestations** are present.

Question 17: A 61-year-old man with CKD stage 5 (eGFR 12 mL/min/1.73m²) presents for pre-dialysis assessment. His blood tests show: haemoglobin 92 g/L, ferritin 380 ng/mL, transferrin saturation 28%, PTH 68 pmol/L (reference 1.6-6.9 pmol/L), corrected calcium 2.28 mmol/L, phosphate 1.89 mmol/L, 25-OH vitamin D 32 nmol/L, bicarbonate 18 mmol/L. Which intervention would address the greatest number of complications in this patient?

A. Commence erythropoietin stimulating agent for anaemia of CKD
B. Start oral alfacalcidol to manage secondary hyperparathyroidism
C. Prescribe oral sodium bicarbonate to correct metabolic acidosis (Correct Answer)
D. Initiate sevelamer as phosphate binder to prevent hyperphosphataemia
E. Arrange renal transplant assessment as definitive treatment

Explanation: ***Prescribe oral sodium bicarbonate to correct metabolic acidosis***- Correcting **metabolic acidosis** (bicarbonate 18 mmol/L) in CKD stage 5 is crucial as it **slows CKD progression**, improves **nutritional status** by reducing protein catabolism, and mitigates **muscle wasting**.- It also benefits **renal bone disease** by decreasing acid buffering from bone, and can enhance the effectiveness of **erythropoietin-stimulating agents** for anaemia.*Commence erythropoietin stimulating agent for anaemia of CKD*- While the patient has **anaemia (Hb 92 g/L)**, commencing an ESA primarily targets only this specific complication.- It does not address the **metabolic acidosis**, **hyperphosphataemia**, or **secondary hyperparathyroidism**, which contribute to broader systemic issues.*Start oral alfacalcidol to manage secondary hyperparathyroidism*- This addresses the **elevated PTH (68 pmol/L)**, but the patient also has **nutritional vitamin D deficiency (25-OH vitamin D 32 nmol/L)**, which should ideally be corrected first or concurrently.- It specifically targets mineral bone disease and doesn't comprehensively address other significant issues like **metabolic acidosis** or **anaemia**.*Initiate sevelamer as phosphate binder to prevent hyperphosphataemia*- While the patient has **hyperphosphataemia (phosphate 1.89 mmol/L)**, this intervention solely focuses on phosphate binding.- It does not provide the broad benefits for **CKD progression**, **nutritional status**, or **acid-base balance** that correcting metabolic acidosis offers.*Arrange renal transplant assessment as definitive treatment*- **Renal transplantation** is the definitive long-term treatment for ESRD, but it is not an immediate intervention to address the current array of biochemical derangements.- Prior to transplantation, patients require **medical stabilization** and optimization of their complications, such as **metabolic acidosis**, to improve surgical outcomes and readiness.

Question 18: A 35-year-old man presents to the emergency department with a 4-hour history of severe right loin pain, haematuria, and vomiting. CT KUB confirms a 4mm stone in the right ureter with mild hydronephrosis. He is treated with IM diclofenac and IV fluids. Six hours later, he develops fever of 38.7°C with rigors. Blood tests show: WBC 17.8 × 10⁹/L, CRP 142 mg/L, creatinine 156 μmol/L (baseline 88 μmol/L). Blood pressure is 98/62 mmHg, pulse 118 bpm. What is the most appropriate immediate management?

A. Start IV broad-spectrum antibiotics and arrange emergency ureteroscopy within 6 hours
B. Start IV antibiotics and arrange urgent percutaneous nephrostomy or retrograde ureteric stenting (Correct Answer)
C. Administer further IV fluids and continue conservative management with oral antibiotics
D. Arrange urgent extracorporeal shock wave lithotripsy under antibiotic cover
E. Start IV antibiotics and arrange elective stone removal after infection resolution in 2-4 weeks

Explanation: ***Start IV antibiotics and arrange urgent percutaneous nephrostomy or retrograde ureteric stenting*** - The patient presents with **obstructive pyelonephritis** (infected hydronephrosis) and clear signs of **urosepsis** (fever, rigors, leukocytosis, AKI, hypotension, tachycardia) in the presence of an obstructing ureteric stone. - **Immediate decompression** of the collecting system via a **percutaneous nephrostomy** or **retrograde ureteric stent** is crucial to drain infected urine and relieve the obstruction, preventing septic shock and further kidney damage; this must be initiated alongside **broad-spectrum IV antibiotics**. *Start IV broad-spectrum antibiotics and arrange emergency ureteroscopy within 6 hours* - While IV antibiotics are essential, **emergency ureteroscopy** is generally contraindicated in active infection and sepsis because the high-pressure irrigation used during the procedure can worsen bacteremia and lead to **septic shock**. - The priority in this critical scenario is urgent **drainage and source control**, which ureteroscopy for stone removal does not safely achieve in the acute septic phase; definitive stone management is typically deferred until the infection is under control. *Administer further IV fluids and continue conservative management with oral antibiotics* - The patient is in a state of **sepsis** with signs of **acute kidney injury** due to an obstructed, infected kidney, which constitutes a medical emergency requiring prompt and active intervention, not conservative management. - **Oral antibiotics** are entirely insufficient for systemic urosepsis, and mere fluid resuscitation without addressing the physical **obstruction** will not resolve the infection or prevent severe clinical deterioration. *Arrange urgent extracorporeal shock wave lithotripsy under antibiotic cover* - **ESWL** is primarily designed for stone fragmentation and does not provide the immediate drainage of infected urine from an obstructed system, which is the most critical intervention for managing **urosepsis**. - Performing ESWL on an acutely infected and obstructed kidney can exacerbate the patient's **sepsis** by potentially forcing bacteria into the bloodstream and does not offer the necessary prompt relief of obstruction and drainage. *Start IV antibiotics and arrange elective stone removal after infection resolution in 2-4 weeks* - Delaying definitive decompression for **2-4 weeks** in a septic patient with an obstructed kidney is life-threatening, as it significantly increases the risk of irreversible septic shock, multi-organ failure, and mortality. - Although IV antibiotics are crucial, the **urgent need for drainage** to relieve the obstruction and eliminate the primary source of infection cannot be postponed in the presence of systemic inflammatory response.

Question 19: A 41-year-old man with autosomal dominant polycystic kidney disease and CKD stage 3a (eGFR 52 mL/min/1.73m²) is commenced on tolvaptan following nephrologist review. He is counselled about potential adverse effects. Which of the following monitoring protocols is most critical for this medication?

A. Monthly full blood count monitoring for bone marrow suppression
B. Weekly serum potassium for risk of hyperkalaemia
C. Monthly urine protein quantification for progression of proteinuria
D. Baseline and regular monthly liver function tests for hepatotoxicity (Correct Answer)
E. Three-monthly echocardiography for valvular heart disease

Explanation: ***Baseline and regular monthly liver function tests for hepatotoxicity***- **Tolvaptan** is associated with a risk of idiosyncratic **drug-induced liver injury (DILI)**, which can be severe or even life-threatening.- Regulatory guidelines mandate **liver function test (LFT)** monitoring at baseline, monthly for the first 18 months, and every 3 months thereafter.*Monthly full blood count monitoring for bone marrow suppression*- **Tolvaptan** is a selective **vasopressin V2 receptor antagonist** and does not have known associations with **myelosuppression**.- Routine **full blood count (FBC)** monitoring is not indicated for patients on this specific therapy.*Weekly serum potassium for risk of hyperkalaemia*- Unlike ACE inhibitors or ARBs, tolvaptan does not typically cause **hyperkalaemia**; its primary electrolyte concern is **hypernatraemia** due to free water clearance.- While monitoring electrolytes is part of general CKD care, weekly **potassium** monitoring is not a specific requirement for tolvaptan safety protocols.*Monthly urine protein quantification for progression of proteinuria*- Tolvaptan is used to slow the increase in **kidney volume** and the decline in **eGFR** in ADPKD, not specifically to manage **proteinuria**.- **Urine protein quantification** is not the primary safety monitoring parameter required for this medication.*Three-monthly echocardiography for valvular heart disease*- There is no clinical evidence linking tolvaptan to the development of **valvular heart disease**.- Regular **echocardiography** is not part of the standard monitoring protocol for patients initiated on **V2 receptor antagonists**.

Question 20: A 67-year-old woman is being investigated for recurrent urinary tract infections. She has had 5 documented UTIs in the past 8 months, each confirmed with positive urine culture and responding to antibiotics. She is postmenopausal and has type 2 diabetes (HbA1c 58 mmol/mol). Renal ultrasound shows normal kidneys with no evidence of obstruction or stones. Post-void bladder scan shows 40 mL residual volume. What is the most appropriate next step in her management?

A. Arrange cystoscopy to exclude bladder pathology
B. Prescribe vaginal oestrogen therapy and review in 3 months (Correct Answer)
C. Commence intermittent self-catheterization to reduce residual volumes
D. Refer to gynaecology for pelvic floor repair surgery
E. Start continuous antibiotic prophylaxis with trimethoprim for 6 months

Explanation: ***Prescribe vaginal oestrogen therapy and review in 3 months***- In **postmenopausal women**, **estrogen deficiency** causes **urogenital atrophy**, leading to changes in vaginal pH and flora (loss of protective lactobacilli), which significantly increases susceptibility to **recurrent UTIs**.- **Topical vaginal estrogen** is the **first-line non-antibiotic treatment** for preventing recurrent UTIs in this population, as it restores the vaginal and urethral mucosa and re-establishes a healthy urogenital microbiome.*Arrange cystoscopy to exclude bladder pathology*- **Cystoscopy** is typically reserved for cases with **haematuria**, suspected bladder cancer, stones, or persistent symptoms despite initial management, none of which are strongly indicated here.- The **renal ultrasound** was normal, and the UTIs respond to antibiotics, suggesting no obvious structural pathology requiring immediate invasive investigation.*Commence intermittent self-catheterization to reduce residual volumes*- A **post-void residual (PVR)** of 40 mL is considered **normal** (typically <50-100 mL), indicating adequate bladder emptying.- **Intermittent self-catheterization** is an invasive procedure indicated for significant urinary retention (PVR >150-200 mL) and would introduce unnecessary risks of infection and discomfort in this patient.*Refer to gynaecology for pelvic floor repair surgery*- There are no signs or symptoms mentioned (e.g., vaginal bulge, pressure, incontinence strongly linked to prolapse) to suggest a significant **pelvic organ prolapse** requiring surgical intervention.- **Pelvic floor repair surgery** is a major intervention and would not be the initial step for recurrent UTIs without clear evidence of severe prolapse contributing significantly to the problem.*Start continuous antibiotic prophylaxis with trimethoprim for 6 months*- **Continuous antibiotic prophylaxis** should generally be considered *after* non-antibiotic measures, such as **vaginal estrogen therapy**, have been tried and failed or are contraindicated.- Immediate long-term antibiotic use increases the risk of **antibiotic resistance** and side effects, making it a second-line approach when an underlying modifiable factor like estrogen deficiency is present.

Question 21: A 57-year-old man with alcoholic liver cirrhosis (Child-Pugh B) presents with increasing abdominal distension and leg oedema. He is treated with therapeutic paracentesis removing 6 litres of ascitic fluid with albumin replacement. Over the next 48 hours, he develops oliguria with urine output 250 mL/24 hours. Blood tests show: sodium 128 mmol/L, potassium 4.2 mmol/L, urea 18.5 mmol/L, creatinine 198 μmol/L (baseline 85 μmol/L), bilirubin 89 μmol/L, albumin 28 g/L. Urinalysis shows sodium <10 mmol/L, no protein, no blood. Renal ultrasound shows normal-sized kidneys with no obstruction. What is the most likely diagnosis?

A. Acute tubular necrosis secondary to hypotension during paracentesis
B. Pre-renal acute kidney injury due to intravascular volume depletion
C. Spontaneous bacterial peritonitis with sepsis-induced AKI
D. Contrast-induced nephropathy from recent CT imaging
E. Hepatorenal syndrome type 1 (Correct Answer)

Explanation: ***Hepatorenal syndrome type 1*** - This diagnosis is characterized by a rapid, progressive rise in **serum creatinine** and **oliguria** in the setting of advanced cirrhosis with ascites, often triggered by events like large-volume paracentesis. - Key supporting features include a **normal renal ultrasound**, extremely low **urinary sodium (<10 mmol/L)**, and failure to improve despite **albumin replacement**, all consistent with intense renal vasoconstriction. *Acute tubular necrosis secondary to hypotension during paracentesis* - In **acute tubular necrosis (ATN)**, urinalysis typically shows granular 'muddy brown' casts and a higher **urinary sodium (>20-40 mmol/L)** due to tubular damage and inability to reabsorb sodium. - The very low urinary sodium in this patient strongly suggests preserved tubular function and intense **renal vasoconstriction**, which is not typical of ATN. *Pre-renal acute kidney injury due to intravascular volume depletion* - While pre-renal AKI also presents with low urinary sodium, it must resolve or significantly improve after adequate **volume expansion** with intravenous fluids or albumin. - This patient received **therapeutic albumin** during the paracentesis yet still progressed to oliguric renal failure, pointing toward the more severe and refractory pathophysiology of **HRS**. *Spontaneous bacterial peritonitis with sepsis-induced AKI* - **Spontaneous bacterial peritonitis (SBP)** is a common precipitant of AKI in cirrhosis, but this patient is not described as having fever, abdominal pain, or an elevated ascitic fluid **neutrophil count**. - While sepsis-induced AKI can lead to renal dysfunction, the clinical timeline specifically follows a **large-volume paracentesis** without other clear signs of infection. *Contrast-induced nephropathy from recent CT imaging* - There is no clinical history provided indicating the patient received **intravenous contrast** for diagnostic imaging prior to the renal deterioration. - **Contrast-induced nephropathy** typically presents with a transient rise in creatinine 48–72 hours post-exposure but is less likely than HRS type 1 in a decompensated cirrhotic patient following a significant physiological stressor like large-volume paracentesis.

Question 22: A 44-year-old woman with CKD stage 4 (eGFR 23 mL/min/1.73m²) secondary to reflux nephropathy attends the pre-dialysis clinic. She asks about different dialysis modalities. Which of the following statements comparing haemodialysis and peritoneal dialysis is most accurate?

A. Peritoneal dialysis provides superior clearance of middle molecules compared to conventional haemodialysis (Correct Answer)
B. Peritoneal dialysis has a higher risk of bacteraemia compared to haemodialysis
C. Peritoneal dialysis provides more stable cardiovascular haemodynamics but has worse long-term patient survival
D. Haemodialysis is associated with better preservation of residual renal function than peritoneal dialysis
E. Haemodialysis requires less dietary restriction than peritoneal dialysis

Explanation: ***Peritoneal dialysis provides superior clearance of middle molecules compared to conventional haemodialysis***- **Peritoneal dialysis (PD)** provides continuous solute exchange, which allows for more efficient removal of larger **middle molecules** (e.g., beta-2 microglobulin) compared to the intermittent nature of **conventional haemodialysis (HD)**.- This enhanced clearance of molecules in PD may help in reducing the long-term risk of **dialysis-related amyloidosis** and other complications.*Peritoneal dialysis has a higher risk of bacteraemia compared to haemodialysis*- **Peritoneal dialysis** is primarily associated with an increased risk of **peritonitis**, an infection of the peritoneal cavity, rather than systemic **bacteraemia**.- **Haemodialysis** carries a significantly higher risk of **bacteraemia** and sepsis due to direct vascular access through **central venous catheters** or arteriovenous fistulas.*Peritoneal dialysis provides more stable cardiovascular haemodynamics but has worse long-term patient survival*- While PD does offer better **haemodynamic stability** due to continuous, gentler fluid removal, most studies show **equivalent long-term survival** rates between the two modalities.- Some evidence even suggests a **survival advantage** for PD during the first few years of treatment, particularly in younger patients without significant comorbidities.*Haemodialysis is associated with better preservation of residual renal function than peritoneal dialysis*- **Peritoneal dialysis** is actually superior for the **preservation of residual renal function (RRF)**, which is a major predictor of patient survival and quality of life.- The rapid fluid shifts and intermittent **hypotensive episodes** common in HD often cause a more precipitous decline in native kidney function.*Haemodialysis requires less dietary restriction than peritoneal dialysis*- **Peritoneal dialysis** patients generally require **fewer dietary restrictions**, especially regarding **potassium** and fluid intake, because the dialysis process is occurring 24/7.- In contrast, HD patients must adhere to stricter diets to prevent the accumulation of toxins and fluid during the **interdialytic intervals**.

Question 23: A 69-year-old man is admitted following a fall. He has been lying on the floor for approximately 18 hours before being found. On admission, his creatinine is 486 μmol/L (baseline 95 μmol/L), creatine kinase 87,000 U/L, potassium 6.4 mmol/L, phosphate 2.8 mmol/L, corrected calcium 1.98 mmol/L, and urine dipstick shows blood 3+ but no red cells on microscopy. ECG shows tall tented T waves. After initial stabilization of hyperkalaemia, what is the most important principle of fluid resuscitation in this patient?

A. Administer 0.9% saline with calcium gluconate to prevent worsening hypocalcaemia
B. Use aggressive fluid resuscitation aiming for urine output >300 mL/hour to prevent renal failure
C. Commence isotonic saline resuscitation while monitoring for hypercalcaemia during recovery phase (Correct Answer)
D. Restrict fluids to 1 L per 24 hours to avoid fluid overload given acute kidney injury
E. Administer hypertonic saline to correct concurrent hyponatraemia and improve renal perfusion

Explanation: ***Commence isotonic saline resuscitation while monitoring for hypercalcaemia during recovery phase***- This patient presents with **rhabdomyolysis-induced acute kidney injury** (AKI) following prolonged immobilization, evidenced by a massive **Creatine Kinase (CK)** elevation and **myoglobinuria** (positive dipstick for blood with no RBCs).- While initial **hypocalcaemia** occurs due to calcium deposition in damaged muscle, monitoring for **rebound hypercalcaemia** during the recovery phase is essential as calcium is released back into the circulation.*Administer 0.9% saline with calcium gluconate to prevent worsening hypocalcaemia*- Calcium replacement should be avoided in rhabdomyolysis unless the patient is **symptomatic** or has life-threatening hyperkalaemia with ECG changes, as it can worsen **extravascular calcification**.- Calcium levels typically rise spontaneously during the recovery phase, making early aggressive supplementation potentially harmful.*Use aggressive fluid resuscitation aiming for urine output >300 mL/hour to prevent renal failure*- While aggressive hydration is the cornerstone of treatment, the target urine output recommended by clinical guidelines is generally **200-300 mL/hour**; aiming consistently higher than 300 mL/hour may increase the risk of **fluid overload** and respiratory complications.- The priority is high-volume **isotonic saline** to flush myoglobin casts from the renal tubules while balancing volume status.*Restrict fluids to 1 L per 24 hours to avoid fluid overload given acute kidney injury*- Fluid restriction is contraindicated in the early management of rhabdomyolysis as it exacerbates **myoglobin-induced tubular toxicity** and worsens AKI.- Aggressive volume expansion is necessary to neutralize the effects of **hypovolaemia** caused by fluid sequestration in damaged muscle tissue.*Administer hypertonic saline to correct concurrent hyponatraemia and improve renal perfusion*- There is no clinical indication for **hypertonic saline** in this scenario, as it could cause rapid osmotic shifts and does not address the underlying pathology of myoglobinuria.- Standard **isotonic crystalloids** (0.9% Saline) are the preferred fluid for expanding extracellular volume and maintaining renal perfusion in patients with crush injuries.

Question 24: A 52-year-old woman with no significant past medical history presents with a 3-day history of fever, dysuria, and left loin pain. Temperature is 38.9°C, BP 108/68 mmHg, pulse 110 bpm. Urine dipstick shows leucocytes 3+, nitrites positive, blood 1+, protein 1+. Which organism is most commonly responsible for this clinical presentation?

A. Staphylococcus saprophyticus
B. Klebsiella pneumoniae
C. Escherichia coli (Correct Answer)
D. Proteus mirabilis
E. Enterococcus faecalis

Explanation: ***Escherichia coli***- **Escherichia coli** is the most common cause of community-acquired **acute pyelonephritis**, responsible for approximately 75% to 95% of cases.- It possesses specialized **P fimbriae** that allow the bacterium to adhere to uroepithelial cells and ascend from the bladder to the **renal parenchyma**.*Staphylococcus saprophyticus*- This organism is a common cause of **uncomplicated cystitis** specifically in young, sexually active females.- It is less frequently associated with ascending **upper urinary tract infections** like pyelonephritis and typically presents within a younger age demographic.*Klebsiella pneumoniae*- While a significant cause of UTIs, it tracks behind E. coli, accounting for roughly 5-10% of cases, often in patients with **comorbidities** like diabetes.- It is a **nitrite-positive** Gram-negative rod but is statistically less likely to be the causative agent in a patient with no significant past medical history.*Proteus mirabilis*- This pathogen is most strongly associated with **urease production**, which leads to an alkaline urine pH and the formation of **struvite (staghorn) calculi**.- Although it causes pyelonephritis, it accounts for only a small percentage of community-acquired cases compared to E. coli.*Enterococcus faecalis*- This is a **Gram-positive coccus** often associated with healthcare-related UTIs, urinary tract instrumentation, or **structural abnormalities**.- Unlike the Gram-negative organisms listed, Enterococcus does not produce nitrites, making it inconsistent with the **nitrite-positive** urine dipstick found in this patient.

Question 25: A 73-year-old man with CKD stage 4 (eGFR 26 mL/min/1.73m²) is admitted with pneumonia. On day 3 of treatment with co-amoxiclav, he becomes confused and develops myoclonic jerks. His renal function has deteriorated with creatinine now 298 μmol/L. EEG shows generalized triphasic waves. Septic screen including blood cultures, lumbar puncture, and CT head are unremarkable. Which of the following is the most likely diagnosis?

A. Uraemic encephalopathy secondary to acute-on-chronic kidney disease
B. Antibiotic-induced encephalopathy from beta-lactam accumulation (Correct Answer)
C. Cerebral abscess with negative neuroimaging
D. New-onset status epilepticus of unknown cause
E. Hyponatraemic encephalopathy

Explanation: ***Antibiotic-induced encephalopathy from beta-lactam accumulation***- The patient's **CKD stage 4** significantly impairs renal excretion, leading to the accumulation of renally cleared drugs like **co-amoxiclav** (a beta-lactam antibiotic). This accumulation can cause **neurotoxicity**, manifesting as confusion and **myoclonic jerks**.- The development of symptoms on day 3 of antibiotic treatment, coupled with characteristic **generalized triphasic waves on EEG** and deteriorating renal function, strongly points to **beta-lactam-induced encephalopathy**. *Uraemic encephalopathy secondary to acute-on-chronic kidney disease*- While **uraemic encephalopathy** can present with confusion and **triphasic waves**, a creatinine of **298 μmol/L** is generally not severe enough to trigger such profound symptoms, especially in a patient with chronic kidney disease who has some metabolic adaptation.- The specific onset of symptoms shortly after initiating **co-amoxiclav** makes a drug-induced cause more likely than a purely metabolic one. *Cerebral abscess with negative neuroimaging*- A **CT head** was unremarkable, effectively ruling out a **cerebral abscess** as the cause of the patient's neurological symptoms. Cerebral abscesses are focal lesions that would typically be visible on imaging.- The patient's symptoms (generalized confusion, myoclonic jerks, diffuse EEG changes) are more consistent with a **diffuse metabolic or toxic encephalopathy** rather than a focal structural lesion. *New-onset status epilepticus of unknown cause*- While the patient experiences myoclonic jerks, the overall clinical picture of confusion and **generalized triphasic waves on EEG** is more indicative of an **encephalopathy** rather than primary **status epilepticus**.- Status epilepticus implies continuous or rapidly recurring seizures. Given the context of **CKD** and a new antibiotic, a toxic/metabolic etiology is far more probable than a primary neurological event. *Hyponatraemic encephalopathy*- This condition typically arises from significant **hyponatraemia** (often Na < 125 mEq/L), leading to cerebral edema and neurological symptoms. No information suggests hyponatraemia in this clinical scenario.- While metabolic encephalopathies can share similar EEG findings, the clear association with a renally cleared drug in a patient with **CKD** makes **drug accumulation** the most specific and likely cause.

Question 26: A 26-year-old woman presents to the emergency department with a 12-hour history of severe left-sided loin pain radiating to the groin, with nausea and haematuria. CT KUB confirms a 7mm stone at the left vesicoureteric junction with moderate hydronephrosis. Her vital signs show temperature 36.8°C, BP 138/82 mmHg, pulse 94 bpm. Blood tests reveal: WBC 11.2 × 10⁹/L, CRP 8 mg/L, creatinine 92 μmol/L. What is the most appropriate initial management?

A. Emergency ureteroscopy and stone extraction
B. Percutaneous nephrostomy insertion
C. Analgesia and trial of conservative management with medical expulsive therapy (Correct Answer)
D. Immediate extracorporeal shock wave lithotripsy (ESWL)
E. Emergency nephrostomy followed by elective ureteroscopy

Explanation: ***Analgesia and trial of conservative management with medical expulsive therapy***- The patient is clinically stable with no signs of **sepsis**, **acute kidney injury**, or intractable pain, making conservative management appropriate even for a **7mm distal ureteric stone**.- **Medical expulsive therapy (MET)** using alpha-blockers like **tamsulosin** can increase the likelihood of spontaneous passage for stones located at the **vesicoureteric junction (VUJ)**.*Emergency ureteroscopy and stone extraction*- This is an **invasive procedure** reserved for patients with failed conservative management, persistent pain, or complications like infection.- It is not indicated as the **initial step** in a hemodynamically stable patient without evidence of renal compromise.*Percutaneous nephrostomy insertion*- This is a method of **surgical decompression** used specifically for an **infected obstructed system** or high-grade obstruction with sepsis.- This patient is **afebrile** with a normal **WBC and CRP**, indicating such an urgent intervention is not currently required.*Immediate extracorporeal shock wave lithotripsy (ESWL)**- **ESWL** is generally less effective for stones located in the **distal ureter** due to the difficulty of targeting and the surrounding pelvic bone structures.- It is not typically performed as an **emergency procedure** in the acute phase of renal colic.*Emergency nephrostomy followed by elective ureteroscopy*- This approach is indicated for **septic obstruction** or **bilateral obstruction**, neither of which is present in this case.- Routine **hydronephrosis** in the setting of a single ureteric stone with normal creatinine does not warrant bypass of the obstruction.

Question 27: A 49-year-old woman with type 2 diabetes and hypertension presents with fatigue. Blood tests show: sodium 138 mmol/L, potassium 4.8 mmol/L, urea 18.2 mmol/L, creatinine 245 μmol/L (baseline 6 months ago was 98 μmol/L), calcium 2.12 mmol/L, phosphate 1.92 mmol/L, albumin 38 g/L, HbA1c 72 mmol/mol. Urine dipstick shows protein 3+, blood negative. Urine ACR is 450 mg/mmol. What is the most likely stage of her chronic kidney disease?

A. CKD stage 2 (eGFR 60-89 mL/min/1.73m²)
B. CKD stage 3a (eGFR 45-59 mL/min/1.73m²)
C. CKD stage 3b (eGFR 30-44 mL/min/1.73m²) (Correct Answer)
D. CKD stage 4 (eGFR 15-29 mL/min/1.73m²)
E. CKD stage 5 (eGFR <15 mL/min/1.73m²)

Explanation: ***CKD stage 3b (eGFR 30-44 mL/min/1.73m²)*** - **Chronic kidney disease (CKD) stage 3b** is characterized by a moderate to severe reduction in kidney function, with an eGFR between **30 and 44 mL/min/1.73m²**. The patient's **creatinine of 245 μmol/L** along with other significant abnormalities indicates a GFR in this severely impaired range. - The notable rise in **creatinine from baseline** (98 to 245 μmol/L), elevated **urea** (18.2 mmol/L), high **phosphate** (1.92 mmol/L), and severe **proteinuria** (ACR 450 mg/mmol, protein 3+) are all consistent with significant renal compromise typical of Stage 3b CKD. *CKD stage 2 (eGFR 60-89 mL/min/1.73m²)* - This stage represents mild GFR reduction, and a **creatinine of 245 μmol/L** is far too high for this category, corresponding instead to significantly impaired function. - The patient's marked **proteinuria (ACR 450 mg/mmol)** and elevated **phosphate** indicate more advanced kidney disease than Stage 2. *CKD stage 3a (eGFR 45-59 mL/min/1.73m²)* - An eGFR in this range would typically be associated with a considerably lower **creatinine** than **245 μmol/L** for a 49-year-old woman. - The presence of symptoms like **fatigue** and significant electrolyte imbalances such as elevated **phosphate** are more typical of later CKD stages. *CKD stage 4 (eGFR 15-29 mL/min/1.73m²)* - This stage denotes severe kidney dysfunction, and while the patient's **creatinine of 245 μmol/L** is high, it is still considered to align with **CKD stage 3b** based on the provided correct option. - Although the patient's symptoms are severe, the eGFR does not yet place her in the **severely impaired (Stage 4)** category if Stage 3b is the most fitting description. *CKD stage 5 (eGFR <15 mL/min/1.73m²)* - This stage signifies **end-stage renal disease (ESRD)**, requiring immediate renal replacement therapy. An eGFR below **15 mL/min/1.73m²** would generally correspond to much higher **creatinine** levels, typically exceeding 400 μmol/L. - The patient's current laboratory values, while indicative of severe CKD, do not yet meet the criteria for **kidney failure** defined by Stage 5.

Question 28: A 64-year-old man with CKD stage 3b (eGFR 37 mL/min/1.73m²) secondary to diabetic nephropathy is started on sodium zirconium cyclosilicate by his nephrologist. His recent blood tests showed potassium 6.2 mmol/L despite dietary modifications. Which of the following best describes the mechanism of action of this medication?

A. Enhances renal potassium excretion by blocking sodium reabsorption in the collecting duct
B. Binds potassium in the gastrointestinal tract in exchange for sodium and hydrogen ions (Correct Answer)
C. Inhibits aldosterone receptors in the distal nephron reducing sodium reabsorption
D. Stimulates insulin release which drives potassium into cells
E. Activates beta-2 adrenergic receptors promoting intracellular potassium shift

Explanation: ***Binds potassium in the gastrointestinal tract in exchange for sodium and hydrogen ions***- **Sodium zirconium cyclosilicate** (SZC) is a highly selective, inorganic **cation exchanger** that captures **potassium ions** throughout the entire **gastrointestinal tract**.- It exchanges **potassium** for **hydrogen and sodium ions**, leading to increased fecal excretion of potassium and a rapid reduction in serum potassium levels, suitable for **chronic hyperkalemia**.*Enhances renal potassium excretion by blocking sodium reabsorption in the collecting duct*- This mechanism describes the action of **potassium-wasting diuretics** (e.g., loop or thiazide diuretics), which increase urinary potassium excretion.- **Sodium zirconium cyclosilicate** acts exclusively within the **gastrointestinal lumen** and does not directly enhance **renal potassium excretion**.*Inhibits aldosterone receptors in the distal nephron reducing sodium reabsorption*- This describes the mechanism of **mineralocorticoid receptor antagonists** (MRAs) like **spironolactone** or **eplerenone**.- MRAs are known to cause or worsen **hyperkalemia** by reducing potassium secretion in the collecting duct, which is contrary to the goal of treating hyperkalemia.*Stimulates insulin release which drives potassium into cells*- This describes the mechanism of **insulin-glucose therapy**, an intervention used for **acute hyperkalemia** to rapidly shift potassium from the extracellular fluid into cells.- **Sodium zirconium cyclosilicate** does not influence **insulin release** or cause an intracellular potassium shift; its action is to remove potassium from the body via the gut.*Activates beta-2 adrenergic receptors promoting intracellular potassium shift*- This is the mechanism of **beta-2 agonists** (e.g., albuterol), which are also used for **acute management of hyperkalemia** to temporarily shift potassium into cells.- Beta-2 agonists do not remove potassium from the body, unlike SZC which binds potassium for **fecal excretion** in chronic settings.

Question 29: A 58-year-old woman undergoes total abdominal hysterectomy for fibroids. On postoperative day 2, her urine output drops to 20 mL over 6 hours. Examination reveals suprapubic fullness and discomfort. Her vital signs are stable with BP 132/78 mmHg and pulse 88 bpm. A bladder scan shows 650 mL of urine. Blood tests reveal creatinine 165 μmol/L (baseline 78 μmol/L) and urea 9.2 mmol/L. What is the most appropriate immediate management?

A. Administer intravenous furosemide 40 mg
B. Insert a urethral catheter (Correct Answer)
C. Urgent renal ultrasound
D. Commence intravenous fluid resuscitation with 0.9% saline
E. Arrange urgent CT abdomen and pelvis with contrast

Explanation: ***Insert a urethral catheter*** - This patient presents with postoperative **acute urinary retention**, evidenced by **oliguria**, **suprapubic fullness**, and a **bladder scan** showing **650 mL** of urine, leading to **post-renal acute kidney injury (AKI)**. - Immediate **urethral catheterization** is the most appropriate management to relieve the **obstruction**, decompress the bladder, and prevent further renal damage. *Administer intravenous furosemide 40 mg* - Administering a **diuretic** like furosemide is contraindicated as it would increase urine production against an already **obstructed outflow tract**, potentially worsening bladder distention and pain. - This intervention fails to address the underlying cause of the patient's **oliguria**, which is mechanical obstruction, not insufficient urine production. *Urgent renal ultrasound* - While a **renal ultrasound** could confirm **hydronephrosis**, the diagnosis of **bladder retention** and its obstructive nature is already clear from the clinical examination and **bladder scan**. - Pursuing further diagnostic imaging at this stage would delay the essential therapeutic intervention of **bladder decompression**, which is the immediate priority. *Commence intravenous fluid resuscitation with 0.9% saline* - **Fluid resuscitation** is indicated for **pre-renal AKI** due to hypovolemia, but this patient's vital signs are stable and the bladder scan confirms adequate urine production. - Providing additional fluids when there is an **outflow obstruction** would exacerbate bladder distention and discomfort without improving urine output or resolving the AKI. *Arrange urgent CT abdomen and pelvis with contrast* - An urgent **CT with contrast** should generally be avoided in patients with a rapidly rising **creatinine** due to the significant risk of **contrast-induced nephropathy**. - This advanced imaging is not immediately necessary as the clinical picture and bladder scan sufficiently identify the **acute urinary obstruction**, requiring immediate catheterization.

Question 30: A 55-year-old woman undergoes parathyroidectomy for primary hyperparathyroidism. Twenty-four hours post-operatively, she develops perioral paraesthesia and carpopedal spasm. Blood tests show: corrected calcium 1.72 mmol/L, phosphate 1.45 mmol/L, magnesium 0.62 mmol/L, PTH 1.2 pmol/L (low). What is the underlying cause of her hypocalcaemia?

A. Hypoparathyroidism due to inadvertent parathyroid gland removal
B. Hungry bone syndrome (Correct Answer)
C. Hypomagnesaemia-induced parathyroid hormone resistance
D. Vitamin D deficiency
E. Acute pancreatitis

Explanation: ***Hungry bone syndrome***- Characterized by rapid **skeletal uptake** of calcium, phosphate, and magnesium following **parathyroidectomy** for chronic hyperparathyroidism.- The crucial diagnostic feature in this patient is the combination of **hypocalcaemia** and **low-normal phosphate**, distinguishing it from hypoparathyroidism which typically presents with hyperphosphataemia.*Hypoparathyroidism due to inadvertent parathyroid gland removal*- Removal of glands causes a lack of PTH, leading to **hypocalcaemia** but characteristically results in **high serum phosphate** due to lost renal phosphate excretion.- While the PTH is low in this case, the **low phosphate** levels point specifically toward bone remineralization rather than simple gland loss.*Hypomagnesaemia-induced parathyroid hormone resistance*- Low magnesium levels can cause **functional hypoparathyroidism** by inhibiting the secretion and peripheral action of PTH.- Though magnesium is low (0.62 mmol/L), the immediate **post-operative context** and low phosphate levels are more specific for the rapid mineral flux seen in **hungry bone syndrome**.*Vitamin D deficiency*- While it can contribute to post-operative hypocalcaemia, it usually presents with a **compensatory rise in PTH** (secondary hyperparathyroidism).- The acute onset of **carpopedal spasms** immediately following surgery is more characteristic of the metabolic shift associated with bone hunger.*Acute pancreatitis*- Can cause hypocalcaemia due to **saponification** of calcium in the retroperitoneum, but this patient's history is specific to neck surgery.- The labs do not match the typical presentation of pancreatitis, and there is no mention of the mandatory **epigastric pain** or elevated amylase/lipase.

Question 31: A 31-year-old woman with HIV infection (CD4 count 180 cells/μL) presents with fever, dysuria, and right loin pain. She appears unwell with temperature 39.2°C, pulse 118/min, BP 102/68 mmHg. Urine dipstick shows blood 3+, leucocytes 3+, nitrites positive. What is the most appropriate initial antibiotic choice?

A. Oral nitrofurantoin 100 mg four times daily for 7 days
B. Intravenous co-amoxiclav 1.2g three times daily
C. Intravenous gentamicin 5 mg/kg once daily plus oral co-trimoxazole (Correct Answer)
D. Intravenous ceftriaxone 2g once daily
E. Oral ciprofloxacin 500 mg twice daily for 14 days

Explanation: ***Intravenous gentamicin 5 mg/kg once daily plus oral co-trimoxazole*** - This patient presents with **acute pyelonephritis** and signs of **sepsis** in the setting of advanced **HIV infection** (CD4 count 180 cells/μL). This combination therapy provides broad-spectrum coverage against common uropathogens and addresses the patient's severe clinical picture. - **Gentamicin** offers potent, rapid bactericidal action against Gram-negative bacteria, which are common causes of pyelonephritis. **Co-trimoxazole** (trimethoprim/sulfamethoxazole) is crucial not only for treating urinary pathogens but also for **Pneumocystis jirovecii pneumonia (PCP) prophylaxis**, which is indicated for HIV patients with CD4 counts below 200 cells/μL. *Oral nitrofurantoin 100 mg four times daily for 7 days* - **Nitrofurantoin** is primarily effective for **uncomplicated cystitis** as it concentrates in the urine and does not achieve adequate therapeutic levels in the renal parenchyma, making it ineffective for **pyelonephritis**. - Oral therapy is unsuitable for a patient presenting with **sepsis** and severe symptoms; **intravenous antibiotics** are required for initial stabilization and better drug delivery. *Intravenous co-amoxiclav 1.2g three times daily* - While an intravenous antibiotic, **co-amoxiclav** has higher rates of **resistance** among common uropathogens, particularly *E. coli*, which is the most frequent cause of pyelonephritis, making it a less reliable empiric choice in severe infections. - This regimen lacks the crucial component of **PCP prophylaxis** provided by co-trimoxazole, which is mandatory for this HIV-positive patient with a low CD4 count. *Intravenous ceftriaxone 2g once daily* - **Ceftriaxone** is a strong intravenous antibiotic and a reasonable choice for complicated pyelonephritis, offering good Gram-negative coverage. However, similar to co-amoxiclav, it does not provide **PCP prophylaxis**. - In immunocompromised patients with a low CD4 count, it is critical to ensure coverage for opportunistic infections like **PCP**, which is addressed by the inclusion of **co-trimoxazole**. *Oral ciprofloxacin 500 mg twice daily for 14 days* - **Ciprofloxacin** is a fluoroquinolone effective against many urinary pathogens, but **oral administration** is inappropriate for a patient presenting with **sepsis** and signs of systemic illness requiring intravenous therapy. - There are increasing concerns about **antibiotic resistance** to fluoroquinolones among uropathogens, and like other monotherapies, it does not address the vital need for **PCP prophylaxis** in this immunocompromised patient.

Question 32: A 78-year-old man with diabetes and CKD stage 3a presents with acute confusion. Blood tests show: sodium 118 mmol/L, potassium 3.8 mmol/L, glucose 6.2 mmol/L, serum osmolality 250 mOsm/kg, urine osmolality 420 mOsm/kg, urine sodium 65 mmol/L. He takes metformin, ramipril, and bendroflumethiazide. What is the most likely cause of his hyponatraemia?

A. Syndrome of inappropriate ADH secretion
B. Thiazide diuretic-induced hyponatraemia (Correct Answer)
C. Hyperglycaemia causing pseudohyponatraemia
D. Primary polydipsia
E. Cerebral salt wasting syndrome

Explanation: ***Thiazide diuretic-induced hyponatraemia*** - **Thiazide diuretics** like **bendroflumethiazide** are a common cause of hyponatraemia in elderly patients, impairing free water excretion by inhibiting sodium reabsorption in the **distal convoluted tubule**. - This mechanism, combined with potential mild **volume depletion** stimulating **ADH secretion**, leads to hypotonic hyponatraemia with elevated urine osmolality and urine sodium, as observed in this patient (Na 118, serum osmolality 250, urine osmolality 420, urine Na 65). *Syndrome of inappropriate ADH secretion* - **SIADH** presents with similar biochemical features of **hypotonic hyponatraemia** (low serum sodium and osmolality) with inappropriately concentrated urine and high urine sodium. - However, **SIADH is a diagnosis of exclusion**, and the patient's use of **bendroflumethiazide**, a medication known to cause hyponatraemia, makes a drug-induced cause much more likely as the primary etiology. *Hyperglycaemia causing pseudohyponatraemia* - **Pseudohyponatraemia** due to **hyperglycaemia** occurs when high glucose draws water into the extracellular space, diluting serum sodium, but the patient's **blood glucose (6.2 mmol/L) is normal**. - The **serum osmolality of 250 mOsm/kg** confirms this is true **hypotonic hyponatraemia**, not an artifact from elevated plasma osmolytes. *Primary polydipsia* - **Primary polydipsia** is characterized by excessive water intake that suppresses **ADH** secretion, leading to the excretion of maximally **dilute urine** (typically urine osmolality <100 mOsm/kg). - This patient's **urine osmolality is high (420 mOsm/kg)**, indicating that ADH is active and the kidneys are concentrating urine, which rules out primary polydipsia. *Cerebral salt wasting syndrome* - **Cerebral salt wasting (CSW)** involves **hyponatraemia**, volume depletion, and high urinary sodium excretion, usually occurring in the context of **intracranial pathology** (e.g., subarachnoid hemorrhage, brain injury). - This patient lacks any history of **neurological insults** or conditions typically associated with CSW, making a drug-induced cause a more plausible explanation for his presentation.

Question 33: A 65-year-old man with CKD stage 4 (eGFR 24 mL/min/1.73m²) presents for routine review. Blood tests show: haemoglobin 92 g/L, MCV 88 fL, ferritin 180 μg/L, transferrin saturation 22%, vitamin B12 and folate normal. He has no evidence of bleeding. What is the most appropriate next step in management of his anaemia?

A. Commence erythropoiesis-stimulating agent (ESA) therapy
B. Prescribe oral iron supplementation
C. Arrange blood transfusion
D. Prescribe intravenous iron therapy (Correct Answer)
E. Arrange bone marrow biopsy

Explanation: ***Prescribe intravenous iron therapy*** - In **CKD Stage 4**, iron stores must be optimized before starting erythropoiesis-stimulating agents (ESAs); **intravenous iron** is preferred as it bypasses **hepcidin-mediated** poor oral absorption. - Although ferritin is 180 μg/L, a **transferrin saturation (TSAT)** of 22% indicates **functional iron deficiency**, requiring replenishment to support erythropoiesis. *Commence erythropoiesis-stimulating agent (ESA) therapy* - ESAs should not be started until **iron stores are fully optimized**, as initiating them in iron-deficient states leads to poor treatment response and can worsen **functional iron deficiency**. - Starting an ESA without adequate available iron (target TSAT often >25-30%) often results in **ESA resistance**, necessitating higher and potentially riskier ESA doses. *Prescribe oral iron supplementation* - **Oral iron** is often poorly tolerated and largely ineffective in advanced CKD due to high **hepcidin levels** which block intestinal iron absorption and utilization. - Clinical guidelines often recommend **intravenous iron** as the first-line iron supplementation strategy for patients with CKD Stage 3-5D (eGFR <45 mL/min/1.73m²) and iron deficiency. *Arrange blood transfusion* - **Blood transfusions** are generally reserved for patients with severe, symptomatic anaemia (e.g., Hb <70 g/L or significant symptoms) or acute bleeding, not for stable, asymptomatic anaemia of CKD at this Hb level (92 g/L). - Transfusion carries risks such as **iron overload**, **allergic reactions**, infection, and **HLA sensitisation**, which can complicate future possibilities for renal transplantation. *Arrange bone marrow biopsy* - A **bone marrow biopsy** is an invasive procedure and is not indicated when the cause of anaemia (anaemia of chronic kidney disease with functional iron deficiency) is already clearly established by clinical context and routine blood tests. - This patient’s **normocytic anaemia**, CKD history, and iron panel abnormalities provide sufficient diagnostic information without needing histological confirmation of marrow function or iron stores.

Question 34: A 43-year-old man presents to the emergency department with a 6-hour history of severe left loin-to-groin pain. Non-contrast CT KUB shows a 7mm calculus at the left vesicoureteric junction with moderate hydronephrosis. He is apyrexial. Creatinine is 110 μmol/L. Pain is controlled with analgesia. What is the most appropriate definitive management?

A. Urgent (within 48 hours) ureteroscopy and stone extraction
B. Medical expulsive therapy with tamsulosin and review in 2-4 weeks (Correct Answer)
C. Immediate percutaneous nephrostomy
D. Extracorporeal shock wave lithotripsy (ESWL)
E. Immediate open ureterolithotomy

Explanation: ***Medical expulsive therapy with tamsulosin and review in 2-4 weeks*** - For ureteric stones **<10mm** in a stable patient without evidence of infection or renal failure, **conservative management** with medical expulsive therapy (MET) is the preferred initial step. - Alpha-blockers like **tamsulosin** relax the smooth muscle of the distal ureter, increasing the passage rate of stones, particularly those at the **vesicoureteric junction**. *Urgent (within 48 hours) ureteroscopy and stone extraction* - Urgent surgical intervention is reserved for patients with **uncontrolled pain**, **sepsis**, or evidence of **acute kidney injury**, none of which are present here. - Routine ureteroscopy is usually planned only if the stone fails to pass after a **trial of conservative management** for several weeks. *Immediate percutaneous nephrostomy* - This procedure is indicated for emergent **decompression** of an **obstructed and infected** collecting system (pyonephrosis). - As the patient is **apyrexial** and hemodynamically stable, invasive decompression is not currently necessary. *Extracorporeal shock wave lithotripsy (ESWL)* - While ESWL is a management option, it is generally less effective than MET for **distal ureteric stones** located at the **vesicoureteric junction** due to bony interference from the pelvis. - Conservative management with MET is less invasive and has a high success rate for stones of this size (**7mm**) in this location. *Immediate open ureterolithotomy* - **Open surgery** is rarely performed in modern practice due to the high success rates of **minimally invasive** endoscopic and lithotripsy techniques. - It is only considered if all other endourological interventions fail or are contraindicated, and it is never the **first-line** choice for a simple 7mm stone.

Question 35: A 36-year-old woman presents with severe nausea and vomiting for 5 days following gastroenteritis. Blood tests show: sodium 142 mmol/L, potassium 2.1 mmol/L, chloride 88 mmol/L, bicarbonate 36 mmol/L, urea 8.2 mmol/L, creatinine 95 μmol/L. Arterial blood gas: pH 7.54, pCO2 6.1 kPa, HCO3- 35 mmol/L. What is the most appropriate initial management?

A. Intravenous 0.9% sodium chloride with added potassium chloride (Correct Answer)
B. Intravenous acetazolamide to correct the alkalosis
C. Oral potassium supplementation alone
D. Intravenous calcium gluconate for cardiac protection
E. Intravenous sodium bicarbonate

Explanation: ***Intravenous 0.9% sodium chloride with added potassium chloride***- The patient presents with **hypochloremic, hypokalemic metabolic alkalosis** due to persistent vomiting; **0.9% saline** is essential to restore volume and provide chloride, which allows the kidneys to excrete bicarbonate.- Severe **hypokalemia (2.1 mmol/L)** requires urgent intravenous replacement, as oral intake is insufficient and likely intolerable due to ongoing vomiting.*Intravenous acetazolamide to correct the alkalosis*- **Acetazolamide** inhibits carbonic anhydrase to increase bicarbonate excretion but significantly increases **urinary potassium loss**, which would be dangerous in this patient.- It is generally reserved for metabolic alkalosis in patients with **fluid overload** (e.g., heart failure) rather than volume-depleted patients.*Oral potassium supplementation alone*- Oral replacement is inappropriate for **severe hypokalemia (<2.5 mmol/L)** and is likely to fail in a patient with active **nausea and vomiting**.- It fails to address the underlying **volume depletion** and chloride deficiency necessary to reverse the metabolic alkalosis.*Intravenous calcium gluconate for cardiac protection*- **Calcium gluconate** is indicated for the emergency treatment of **hyperkalemia** with ECG changes to stabilize the myocardium.- It has no role in treating **hypokalemia** and will not correct the patient's electrolyte or acid-base derangements.*Intravenous sodium bicarbonate*- Administering **sodium bicarbonate** would exacerbate the existing **metabolic alkalosis** (pH 7.54) and further increase bircarbonate levels.- This intervention is contraindicated in this scenario as it would worsen the patient's clinical condition.

Question 36: A 51-year-old man with end-stage renal failure on peritoneal dialysis for 3 years presents with abdominal pain and cloudy dialysate effluent. Dialysate white cell count is 450 cells/μL with 75% neutrophils. Gram stain shows no organisms. Cultures are pending. What is the most appropriate initial antibiotic regimen?

A. Intraperitoneal vancomycin and gentamicin
B. Oral ciprofloxacin
C. Intravenous ceftriaxone
D. Intraperitoneal cefazolin and ceftazidime (Correct Answer)
E. Intravenous meropenem

Explanation: ***Intraperitoneal cefazolin and ceftazidime*** - This patient meets the criteria for **peritoneal dialysis-associated peritonitis** (abdominal pain, cloudy dialysate, high WBC count with neutrophilic predominance). The **intraperitoneal (IP) route** is the preferred delivery method to achieve high local drug concentrations at the site of infection. - Empiric therapy must cover both **Gram-positive** (e.g., coagulase-negative staphylococci, S. aureus) and **Gram-negative** (e.g., Pseudomonas aeruginosa, Enterobacteriaceae) organisms. **Cefazolin** provides Gram-positive coverage, and **ceftazidime** covers Gram-negative organisms, making this a preferred non-toxic combination. *Intraperitoneal vancomycin and gentamicin* - While this combination offers broad-spectrum coverage, **vancomycin** is generally reserved for patients with a known history of **MRSA infection** or significant cephalosporin allergy, which is not indicated in this case. - **Gentamicin** carries a higher risk of **ototoxicity** and **nephrotoxicity** compared to third-generation cephalosporins, especially in patients with some residual renal function. *Oral ciprofloxacin* - **Oral administration** is inappropriate for initial empiric therapy in acute PD peritonitis as it does not reliably achieve the required **bactericidal concentrations** in the peritoneal fluid quickly enough to effectively manage the acute infection. - **Ciprofloxacin** alone does not provide sufficient broad-spectrum coverage for both common Gram-positive and Gram-negative organisms typically implicated in PD peritonitis. *Intravenous ceftriaxone* - The **intravenous route** is less effective than **intraperitoneal administration** for localized peritonitis because it delivers lower drug concentrations directly to the peritoneal cavity, which is the primary site of infection. - Single-agent therapy with **ceftriaxone** does not provide adequate coverage for all potential **Gram-negative pathogens**, particularly *Pseudomonas aeruginosa*, which is a significant concern in PD peritonitis. *Intravenous meropenem* - Using an **ultra-broad spectrum** carbapenem like meropenem intravenously as initial empiric therapy is typically reserved for very severe cases, those with signs of sepsis, or when multi-drug resistant organisms are highly suspected, to avoid promoting **antibiotic resistance**. - Similar to other IV options, it fails to provide the superior **local bioavailability** achieved through **intraperitoneal administration**, which is critical for effective treatment of peritoneal infection.

Question 37: A 24-year-old woman presents to her GP with a 24-hour history of dysuria and urinary frequency. She is otherwise well, not pregnant, and has no past medical history. Temperature is 37.1°C. Urinalysis shows leucocytes 2+, nitrites positive, no blood. What is the most appropriate management?

A. Urine culture then start empirical antibiotics
B. Immediate empirical antibiotic treatment without urine culture (Correct Answer)
C. Urine culture and withhold antibiotics pending results
D. Arrange urgent ultrasound of renal tract
E. Advise increased fluid intake and symptomatic treatment only

Explanation: ***Immediate empirical antibiotic treatment without urine culture***- In **non-pregnant women** with simple **uncomplicated urinary tract infections**, the diagnosis can be made based on typical symptoms like **dysuria** and **frequency** combined with **positive nitrites** on dipstick.- National guidelines (NICE) recommend starting immediate antibiotics (e.g., nitrofurantoin or trimethoprim) without the need for a **urine culture**, as it is unlikely to change the initial management.*Urine culture then start empirical antibiotics*- A **urine culture** is not routinely indicated for **uncomplicated cystitis** in a healthy, non-pregnant female where symptoms and dipstick are definitive.- Performing a culture in this scenario is considered unnecessary and is generally reserved for **recurrent UTIs** or cases where **empirical treatment fails**.*Urine culture and withhold antibiotics pending results*- Withholding treatment while waiting for culture results is inappropriate as it causes unnecessary suffering and increases the risk of the infection ascending to the **upper urinary tract**.- Most cases of cystitis are caused by **E. coli**, which is reliably treated with **first-line empirical antibiotics**.*Arrange urgent ultrasound of renal tract*- A **renal ultrasound** is not indicated for a first presentation of an uncomplicated lower UTI with no features of **pyelonephritis** (e.g., loin pain or high fever).- Imaging is typically reserved for patients with **recurrent infections**, suspected **renal stones**, or structural abnormalities.*Advise increased fluid intake and symptomatic treatment only*- While hydration and **analgesia** are helpful adjuncts, they are not a substitute for antibiotic therapy in a patient with a **confirmed bacterial UTI** (nitrite positive).- Delayed treatment can lead to prolonged morbidity and a higher risk of developing **pyelonephritis**.

Question 38: A 59-year-old man with chronic hepatitis C and compensated cirrhosis presents to the emergency department with oliguria. He has been taking NSAIDs for back pain. Blood results show: urea 32 mmol/L, creatinine 380 μmol/L (baseline 85 μmol/L), sodium 128 mmol/L, potassium 5.8 mmol/L. Urinalysis shows no blood or protein. Urinary sodium is 8 mmol/L. What is the most likely diagnosis?

A. Acute tubular necrosis
B. Hepatorenal syndrome (Correct Answer)
C. Prerenal acute kidney injury
D. Acute interstitial nephritis
E. Rapidly progressive glomerulonephritis

Explanation: ***Hepatorenal syndrome*** - Characterized by **functional renal failure** in patients with **cirrhosis**, often precipitated by factors like **NSAIDs** (which inhibit renal vasodilatory prostaglandins) leading to intense renal vasoconstriction. - Key diagnostic features include **oliguria**, significant increase in **creatinine** (from 85 to 380 μmol/L), **hyponatremia** (128 mmol/L), **hyperkalemia** (5.8 mmol/L), and a **very low urinary sodium (< 10 mmol/L)** (8 mmol/L in this case), indicating avid sodium retention with a **bland urinalysis**. *Acute tubular necrosis* - Typically presents with a **urinary sodium > 40 mmol/L** and often low urine osmolality, as the tubules lose their ability to reabsorb sodium and concentrate urine. - **Urinalysis** would classically reveal **muddy brown granular casts** and renal tubular epithelial cells, which are absent in this patient's bland sediment. *Prerenal acute kidney injury* - While sharing features like **low urinary sodium (< 20 mmol/L)** and **oliguria**, it usually improves rapidly with **volume expansion**. - The context of **cirrhosis** and sustained kidney injury despite initial volume status suggests a more severe vasoconstrictive process like HRS, where the effective circulating volume is severely diminished due to splanchnic vasodilation. *Acute interstitial nephritis* - Often drug-induced (including NSAIDs) but typically presents with **sterile pyuria**, white blood cell casts, and sometimes **eosinophiluria**. - Clinical features such as fever, rash, and arthralgia are frequently present, and the urinalysis here does not support this diagnosis. *Rapidly progressive glomerulonephritis* - Characterized by an **active urinary sediment** containing **dysmorphic red blood cells** and **red cell casts**, indicative of glomerular inflammation. - It also typically involves significant **proteinuria and hematuria**, both of which are explicitly stated as absent in this patient's urinalysis.

Question 39: A 47-year-old woman with newly diagnosed IgA nephropathy is found to have persistent haematuria and an albumin:creatinine ratio of 95 mg/mmol despite 4 months of maximal tolerated ACE inhibitor therapy and blood pressure control <130/80 mmHg. eGFR is 52 mL/min/1.73m². What is the most appropriate next step in management?

A. Add a systemic corticosteroid such as oral prednisolone (Correct Answer)
B. Commence mycophenolate mofetil
C. Add a sodium-glucose co-transporter-2 inhibitor
D. Perform a repeat renal biopsy to assess disease activity
E. Refer for plasma exchange therapy

Explanation: ***Add a systemic corticosteroid such as oral prednisolone*** - Per **KDIGO 2021 guidelines**, patients with **IgA nephropathy** and persistent **proteinuria >0.75-1 g/day** (ACR 95 mg/mmol) despite 90 days of optimized supportive care should be considered for **corticosteroid therapy**. - This patient has a preserved **eGFR (>30 mL/min/1.73m²)**, making her a candidate for a 6-month course of steroids to reduce the risk of progressive renal decline. *Commence mycophenolate mofetil* - **Mycophenolate mofetil (MMF)** is generally not recommended as first-line immunosuppression in the general IgA nephropathy population due to inconsistent trial data. - It is sometimes considered as a **steroid-sparing agent** in specific populations (e.g., Chinese patients), but **systemic corticosteroids** remain the standard evidence-based next step. *Add a sodium-glucose co-transporter-2 inhibitor* - While **SGLT2 inhibitors** provide cardiovascular and renal protection in chronic kidney disease, they are typically integrated into **supportive care** rather than replacing indicated immunosuppression for high-risk IgA disease. - The priority here is addressing the high inflammatory risk and **proteinuria** that has failed maximal **ACE inhibitor** therapy. *Perform a repeat renal biopsy to assess disease activity* - A **repeat renal biopsy** is not routinely indicated as the initial diagnosis of IgA nephropathy is already established and clinical markers (**ACR** and **eGFR**) guide treatment. - Biopsy may be revisited only if there is an unexpectedly rapid decline in renal function suggesting a **crescentic transformation** or a secondary pathology. *Refer for plasma exchange therapy* - **Plasma exchange** has no established role in the routine management of **IgA nephropathy**. - It is reserved for severe small-vessel vasculitis conditions like **ANCA-associated vasculitis** or **anti-GBM disease**, particularly when involving pulmonary hemorrhage.

Question 40: A 33-year-old woman presents with fever, dysuria, and right-sided loin pain. She is 8 weeks pregnant with her first child. Temperature is 38.7°C, pulse 105/min, BP 118/72 mmHg. Urinalysis shows leucocytes 3+, nitrites positive, protein 1+. What is the most appropriate initial antibiotic treatment?

A. Oral nitrofurantoin 100 mg twice daily for 7 days
B. Intravenous cefuroxime 750 mg three times daily (Correct Answer)
C. Oral trimethoprim 200 mg twice daily for 7 days
D. Oral ciprofloxacin 500 mg twice daily for 7 days
E. Intramuscular gentamicin 5 mg/kg once daily

Explanation: ***Intravenous cefuroxime 750 mg three times daily***- This patient presents with **acute pyelonephritis** in pregnancy, evidenced by fever, **loin pain**, and systemic symptoms, which necessitates hospital admission and initial **intravenous antibiotic** therapy.- **Cefuroxime**, a second-generation cephalosporin, is considered safe in all trimesters of pregnancy and effectively covers common **Gram-negative uropathogens** like E. coli.*Oral nitrofurantoin 100 mg twice daily for 7 days*- **Nitrofurantoin** is primarily used for uncomplicated cystitis and does not achieve adequate therapeutic concentrations in the **renal parenchyma** to treat pyelonephritis.- While generally safe in early pregnancy, it should be avoided near **term** due to the risk of neonatal **haemolysis**, particularly in infants with G6PD deficiency.*Oral trimethoprim 200 mg twice daily for 7 days*- **Trimethoprim** is an anti-folate drug and is **contraindicated** in the **first trimester** of pregnancy due to its association with an increased risk of **neural tube defects**.- Oral therapy is insufficient for a febrile patient with systemic signs of **upper urinary tract infection** requiring inpatient management.*Oral ciprofloxacin 500 mg twice daily for 7 days*- **Quinolones** like ciprofloxacin are generally **contraindicated in pregnancy** due to concerns regarding potential **arthropathy** and adverse effects on **fetal cartilage development**.- Oral administration is not the appropriate initial route for managing **febrile pyelonephritis** and associated systemic illness.*Intramuscular gentamicin 5 mg/kg once daily*- While effective against Gram-negative bacteria, **aminoglycosides** such as gentamicin carry a significant risk of **fetal ototoxicity** and **nephrotoxicity**.- **Cephalosporins** are preferred first-line agents in pregnant patients with pyelonephritis; gentamicin is typically reserved for severe infections or documented resistant organisms.

Question 41: A 68-year-old man with prostate cancer on abiraterone presents with muscle weakness and palpitations. ECG shows flattened T waves and prominent U waves. Blood tests reveal: sodium 138 mmol/L, potassium 2.4 mmol/L, bicarbonate 32 mmol/L, chloride 92 mmol/L. Arterial blood gas shows pH 7.52, pCO2 5.8 kPa. What is the underlying mechanism of his electrolyte disturbance?

A. Increased aldosterone activity due to inhibition of 17α-hydroxylase (Correct Answer)
B. Primary hyperaldosteronism due to adrenal adenoma
C. Renal tubular acidosis type 1
D. Gastrointestinal potassium loss
E. Insulin-induced intracellular potassium shift

Explanation: ***Increased aldosterone activity due to inhibition of 17α-hydroxylase***- **Abiraterone** inhibits the **CYP17A1** enzyme, blocking the conversion of pregnenolone and progesterone into cortisol precursors, which leads to a compensatory increase in **ACTH**.- Elevated **ACTH** drives the accumulation of mineralocorticoid precursors like **11-deoxycorticosterone**, resulting in **hypokalemia**, **metabolic alkalosis**, and clinical symptoms such as muscle weakness and palpitations.*Primary hyperaldosteronism due to adrenal adenoma*- While this condition presents with **hypokalemia** and **metabolic alkalosis**, the direct cause in this patient is his **abiraterone** therapy.- Primary hyperaldosteronism is typically characterized by **suppressed renin activity**, which differs from the mechanism induced by abiraterone where ACTH drives mineralocorticoid excess.*Renal tubular acidosis type 1*- **Type 1 (Distal) RTA** is characterized by **metabolic acidosis** (low bicarbonate and pH), which contradicts the patient's **metabolic alkalosis** (high bicarbonate and pH).- Although hypokalemia can be present, the primary acid-base derangement is opposite to that observed in this case.*Gastrointestinal potassium loss*- **Gastrointestinal potassium loss**, such as from diarrhea, typically causes a **hyperchloremic metabolic acidosis** due to bicarbonate loss.- While severe vomiting can cause metabolic alkalosis and hypokalemia, the patient's specific medication (**abiraterone**) points to a more direct endocrine mechanism.*Insulin-induced intracellular potassium shift*- Insulin causes a temporary shift of **potassium into cells**, leading to **transient hypokalemia**.- This mechanism does not account for the profound and sustained **metabolic alkalosis** or the presence of prominent U waves and flattened T waves, which suggest chronic potassium depletion.

Question 42: A 56-year-old woman with type 2 diabetes and hypertension presents with fatigue and ankle swelling. Blood results show: creatinine 145 μmol/L, eGFR 38 mL/min/1.73m², HbA1c 62 mmol/mol. Urinalysis reveals albumin:creatinine ratio 45 mg/mmol. Which classification of chronic kidney disease does this patient have?

A. CKD G3a A3
B. CKD G3b A3 (Correct Answer)
C. CKD G3a A2
D. CKD G3b A2
E. CKD G2 A3

Explanation: ***CKD G3b A3*** - The patient's **eGFR of 38 mL/min/1.73m²** falls into the **G3b category**, which defines a moderate-to-severe reduction in kidney function (range **30–44 mL/min/1.73m²**). - An albumin:creatinine ratio (ACR) of **45 mg/mmol** is categorized as **A3**, representing **severely increased albuminuria** (>30 mg/mmol). *CKD G3a A3* - **G3a** classification is reserved for patients with an eGFR between **45–59 mL/min/1.73m²**, which is higher than this patient's level of 38. - While the albuminuria (A3) is correct, the **filtration stage (G3a vs G3b)** is underestimated for the patient's actual eGFR. *CKD G3a A2* - This option incorrectly states both the **eGFR stage (G3a)** and the **albuminuria stage (A2)** based on the patient's values. - **A2** represents **moderately increased albuminuria** (3–30 mg/mmol), whereas this patient's ACR of 45 mg/mmol indicates **severely increased albuminuria (A3)**. *CKD G3b A2* - While the **G3b** stage correctly identifies the eGFR range of **30–44 mL/min/1.73m²**, the albuminuria stage (A2) is incorrect. - **A2** is for an ACR of **3–30 mg/mmol**, failing to account for the patient's higher clinical value of **45 mg/mmol**, which is **A3**. *CKD G2 A3* - **G2** defines a **mildly decreased GFR** of **60–89 mL/min/1.73m²**, which is significantly higher than this patient's eGFR of 38. - This stage would imply much better preserved kidney function than what is demonstrated by her **creatinine of 145 μmol/L** and **eGFR of 38**.

Question 43: A 42-year-old man with a history of gout is brought to the emergency department by ambulance after a grand mal seizure. He recently started chemotherapy for Burkitt lymphoma. Blood tests show: sodium 136 mmol/L, potassium 7.2 mmol/L, urea 28 mmol/L, creatinine 420 μmol/L (baseline 95 μmol/L), phosphate 2.8 mmol/L, calcium 1.85 mmol/L, urate 780 μmol/L. ECG shows peaked T waves. What is the most appropriate immediate management?

A. Intravenous calcium gluconate 10 mL of 10% solution (Correct Answer)
B. Intravenous rasburicase 0.2 mg/kg
C. Intravenous sodium bicarbonate 8.4% solution
D. Emergency haemodialysis
E. Intravenous allopurinol 200 mg

Explanation: ***Intravenous calcium gluconate 10 mL of 10% solution*** - This patient has severe **hyperkalaemia (7.2 mmol/L)** with **ECG changes (peaked T waves)**, which is a life-threatening emergency requiring immediate **myocardial membrane stabilization**. - Calcium gluconate acts within minutes to reduce the risk of **ventricular arrhythmias** and cardiac arrest, though it does not lower the serum potassium level itself. *Intravenous rasburicase 0.2 mg/kg* - While rasburicase is the preferred agent for managing **hyperuricaemia** in **Tumour Lysis Syndrome**, it does not address the immediate cardiac risk from hyperkalaemia. - It acts by converting **uric acid** to allantoin, which is more soluble, but it will not stabilize the heart or lower potassium levels. *Intravenous sodium bicarbonate 8.4% solution* - Sodium bicarbonate can sometimes be used to shift potassium intracellularly in the setting of **metabolic acidosis**, but it is not the first-line treatment for **cardiac stabilization**. - Routine use is generally avoided unless severe acidosis is present, as it can worsen **hypocalcaemia** by increasing calcium binding to albumin. *Emergency haemodialysis* - Haemodialysis is the **definitive treatment** for the severe electrolyte derangements and **Acute Kidney Injury (AKI)** seen in this patient's Tumour Lysis Syndrome. - However, it cannot be initiated instantly; **calcium gluconate** must be given first to protect the heart while the dialysis team and equipment are being prepared. *Intravenous allopurinol 200 mg* - Allopurinol is used to block the production of **uric acid** by inhibiting **xanthine oxidase**, primarily as prophylaxis rather than acute treatment. - It is ineffective at reducing existing high levels of uric acid and has no role in the emergency management of **hyperkalaemic ECG changes**.

Question 44: A 77-year-old man with CKD stage 3b (eGFR 42 mL/min/1.73m²) presents with 2 days of confusion. Medications include amlodipine, bisoprolol, furosemide, and sodium valproate for epilepsy. Blood tests reveal: sodium 128 mmol/L, potassium 3.8 mmol/L, urea 8.2 mmol/L, creatinine 156 µmol/L (baseline 148 µmol/L), glucose 5.4 mmol/L, serum osmolality 268 mOsm/kg, urine osmolality 520 mOsm/kg, urine sodium 58 mmol/L. Clinical examination shows mild peripheral oedema, BP 158/92 mmHg. Chest X-ray and CT head are normal. Which additional test would be most helpful in determining the underlying cause?

A. Chest CT to exclude malignancy
B. Thyroid function tests (Correct Answer)
C. Serum cortisol and ACTH stimulation test
D. Serum valproate level
E. Brain natriuretic peptide (BNP)

Explanation: ***Thyroid function tests*** - This patient presents with **hypotonic hyponatraemia** (Na 128, serum osmolality 268) and **inappropriately concentrated urine** (urine osmolality 520, urine Na 58), consistent with **SIADH** or a similar syndrome of impaired free water excretion. - **Hypothyroidism** is a well-known, albeit rare, cause of hyponatraemia due to impaired free water excretion and can present with confusion, making **thyroid function tests** essential to exclude this reversible cause. *Serum cortisol and ACTH stimulation test* - **Adrenal insufficiency** can cause hyponatraemia, but it typically presents with **hypotension** and often **hyperkalaemia**. - The patient's **blood pressure is elevated (158/92 mmHg)** and **potassium is normal**, which makes adrenal insufficiency a less likely primary cause in this scenario. *Serum valproate level* - **Sodium valproate** is a known pharmacological cause of SIADH, but a serum level would confirm exposure rather than definitively establishing it as the *sole* or *primary* cause of the hyponatraemia, especially when other conditions like hypothyroidism need to be ruled out. - Management of valproate-induced hyponatraemia usually involves dose adjustment or cessation, and the level itself doesn't guide the initial diagnostic workup for *other* potential underlying causes. *Brain natriuretic peptide (BNP)* - **Heart failure** causes **hypervolemic hyponatraemia**, where the body attempts to retain fluid, leading to **low urine sodium** (<20 mmol/L) due to avid renal sodium reabsorption. - This patient has a **high urine sodium (58 mmol/L)** and a **normal chest X-ray**, which makes heart failure an unlikely primary cause of this specific pattern of hyponatraemia. *Chest CT to exclude malignancy* - While **malignancies** (e.g., small cell lung cancer) are classic causes of **paraneoplastic SIADH**, a **normal chest X-ray** reduces its immediate diagnostic priority. - It is typically considered after more common or readily reversible endocrine causes, like hypothyroidism, have been evaluated, especially given the patient's age and general presentation.

Question 45: A 39-year-old woman presents to the emergency department with severe colicky right flank pain radiating to the groin, nausea, and visible haematuria. Non-contrast CT KUB reveals a 5mm calculus at the right vesicoureteric junction and a density measurement of 1200 Hounsfield units. Creatinine is 68 µmol/L, she is apyrexial, and there is no hydronephrosis. Pain is controlled with diclofenac. She wishes to know the likelihood of spontaneous passage and optimal management strategy.

A. Extracorporeal shockwave lithotripsy within 48 hours offers best stone-free rate for distal stones
B. The stone will likely pass spontaneously; discharge with analgesia and alpha-blocker, review in 4 weeks (Correct Answer)
C. Stone density >1000 HU indicates calcium composition; immediate ureteroscopy is recommended
D. Conservative management unlikely to succeed; admit for intervention within 48 hours
E. The location suggests spontaneous passage unlikely; arrange elective ureteroscopy in 2 weeks

Explanation: ***The stone will likely pass spontaneously; discharge with analgesia and alpha-blocker, review in 4 weeks***- Ureteral stones **≤5mm** at the **vesicoureteric junction (VUJ)** have a high probability (approximately 70-80%) of **spontaneous passage** within four weeks.- Management of uncomplicated renal colic involves outpatient **medical expulsive therapy (MET)** with an **alpha-blocker** (e.g., tamsulosin), adequate analgesia, and follow-up to confirm stone clearance.*Extracorporeal shockwave lithotripsy within 48 hours offers best stone-free rate for distal stones*- **ESWL** is generally less effective for stones located in the **distal ureter** compared to stones in the upper ureter or kidney due to shielding by the pelvic bone.- Immediate intervention is not recommended for an **uncomplicated 5mm stone** where conservative management is the first-line approach with a high success rate.*Stone density >1000 HU indicates calcium composition; immediate ureteroscopy is recommended*- A high **Hounsfield Unit (HU)** value, such as 1200, suggests a dense stone (e.g., **calcium oxalate monohydrate**), but stone hardness alone does not mandate immediate surgical intervention for stable patients.- **Ureteroscopy** is a definitive treatment if conservative management fails, but it is not indicated as an initial step for small, non-obstructive, uncomplicated stones.*Conservative management unlikely to succeed; admit for intervention within 48 hours*- **Admission** and urgent intervention are typically reserved for complicated cases such as intractable pain, **urosepsis (fever, signs of infection)**, or **acute kidney injury** due to obstruction, none of which are present.- The patient's pain is well-controlled with **NSAIDs**, and there is no evidence of hydronephrosis or infection, making conservative management appropriate.*The location suggests spontaneous passage unlikely; arrange elective ureteroscopy in 2 weeks*- While the **vesicoureteric junction (VUJ)** is a common site for stones to lodge, a 5mm stone that has reached this point still has a good chance of spontaneous passage, especially with MET.- **Elective ureteroscopy** is usually considered for stones that fail to pass after an adequate trial (e.g., 4-6 weeks) of conservative management or for larger stones, not prematurely after 2 weeks for an uncomplicated 5mm stone.

Question 46: A 63-year-old man with CKD stage 5 (eGFR 11 mL/min/1.73m²) is being counselled about renal replacement therapy options. He lives alone, works part-time, and wishes to maintain independence. He has well-controlled diabetes, previous myocardial infarction with good LV function, and a BMI of 32 kg/m². He expresses concern about needle phobia and wishes to minimize hospital visits. Which renal replacement modality would be most appropriate to recommend?

A. In-centre haemodialysis three times per week
B. Automated peritoneal dialysis (APD) (Correct Answer)
C. Conservative kidney management without dialysis
D. Continuous ambulatory peritoneal dialysis (CAPD)
E. Home haemodialysis

Explanation: ***Automated peritoneal dialysis (APD)*** - **APD** is the most suitable as it uses an overnight **cycler machine**, allowing the patient to remain independent and continue his **part-time work** during the day. - It specifically addresses his **needle phobia** by using a **Tenckhoff catheter** instead of fistula cannulation and significantly **reduces hospital visits** (usually once per month).*In-centre haemodialysis three times per week* - This modality requires frequent **hospital visits** and significant travel time, which contradicts the patient's desire for **independence** and minimized clinical contact. - It involves regular **needle cannulation** of an arteriovenous fistula or graft, which is incompatible with the patient's severe **needle phobia**.*Conservative kidney management without dialysis* - This is typically reserved for elderly patients with significant **frailty**, multiple severe comorbidities, or poor functional status who do not wish to undergo RRT. - Given his **good LV function**, active work status, and lack of severe cognitive impairment, choosing this would prematurely forfeit the potential **survival benefit** of dialysis.*Continuous ambulatory peritoneal dialysis (CAPD)* - CAPD requires performing multiple **manual exchanges** throughout the day, which can be disruptive for a patient who is still **working part-time**. - While it avoids needles, it offers less **lifestyle flexibility** and daytime freedom compared to the automated machinery used in **APD**.*Home haemodialysis* - Although it provides high levels of independence and home-based care, it explicitly requires **self-cannulation** with needles multiple times per week. - This is generally contraindicated or highly stressful for patients with a documented, significant **needle phobia**.

Question 47: A 52-year-old man undergoes cadaveric renal transplantation for end-stage renal disease secondary to IgA nephropathy. He receives basiliximab induction and is maintained on tacrolimus, mycophenolate, and prednisolone. On post-operative day 5, his creatinine rises from 145 µmol/L to 265 µmol/L. Urine output drops to 0.4 mL/kg/hr. Tacrolimus level is 8 µg/L (target 10-15). Transplant ultrasound shows normal perfusion but mild collecting system dilatation. What is the most appropriate next investigation?

A. Transplant biopsy (Correct Answer)
B. Nuclear medicine MAG3 renogram
C. CT angiography of transplant renal artery
D. Increase tacrolimus dose and recheck level in 48 hours
E. Urinary BK virus PCR

Explanation: ***Transplant biopsy*** - A **transplant biopsy** is the **gold standard** for diagnosing acute graft dysfunction early post-transplant, definitively distinguishing between **acute cellular rejection (ACR)**, **antibody-mediated rejection (AMR)**, and **acute tubular necrosis (ATN)**. - This patient's rapidly rising creatinine and oliguria on day 5, despite a subtherapeutic tacrolimus level, warrant histological confirmation to guide appropriate and specific treatment. *Nuclear medicine MAG3 renogram* - This test assesses **perfusion** and **urinary outflow**, which can be helpful for diagnosing **urine leaks** or significant obstruction that might not be fully evident on ultrasound. - However, the **transplant ultrasound** already showed normal perfusion and only mild collecting system dilatation, suggesting less utility compared to a biopsy for differentiating the underlying cause of acute kidney injury. *CT angiography of transplant renal artery* - This investigation is indicated for suspected **renal artery stenosis** or **thrombosis**, which would typically present with abnormal graft perfusion on ultrasound or severe hypertension. - Since the **ultrasound showed normal perfusion**, and the use of **intravenous contrast** carries a risk of **nephrotoxicity** in a patient with a failing graft, it is not the most appropriate initial investigation. *Increase tacrolimus dose and recheck level in 48 hours* - While the **tacrolimus level is subtherapeutic** (8 µg/L vs. target 10-15 µg/L), increasing the dose empirically without a definitive diagnosis is risky, as calcineurin inhibitors can exacerbate **acute tubular necrosis (ATN)**. - Relying on a dose adjustment delays the critical diagnosis of **acute rejection**, which requires prompt and specific immunosuppressive therapy beyond simply increasing maintenance medication. *Urinary BK virus PCR* - **BK virus-associated nephropathy (BKVAN)** typically presents much later in the post-transplant course, usually between **3 to 12 months** after transplantation, when immunosuppression is more established. - Investigating for BK virus on **post-operative day 5** is premature and highly unlikely to be the cause of this acute and early graft dysfunction.

Question 48: A 71-year-old woman with diabetes and hypertension presents with progressive confusion over 3 days. Blood tests show: sodium 118 mmol/L, potassium 4.2 mmol/L, urea 3.8 mmol/L, creatinine 76 µmol/L, glucose 6.8 mmol/L, serum osmolality 248 mOsm/kg, urine osmolality 445 mOsm/kg, urine sodium 52 mmol/L. She takes bendroflumethiazide, ramipril, atorvastatin, and metformin. Clinical examination shows moist mucous membranes, no oedema, and blood pressure 138/82 mmHg. What is the most likely cause of her hyponatraemia?

A. Syndrome of inappropriate ADH secretion
B. Thiazide diuretic use (Correct Answer)
C. Cerebral salt wasting
D. Primary polydipsia
E. Adrenal insufficiency

Explanation: ***Thiazide diuretic use*** - **Bendroflumethiazide** is a common cause of profound hyponatraemia in elderly women by blocking sodium reabsorption in the **distal convoluted tubule**, which impairs the kidney's ability to dilute urine. - The biochemical profile mimics SIADH (low serum osmolality, **urine osmolality >100 mOsm/kg**, and high urine sodium), but the presence of a causative medication makes this the most likely diagnosis. *Syndrome of inappropriate ADH secretion* - While the biochemistry matches **euvolaemic hypotonic hyponatraemia**, SIADH is a diagnosis of exclusion that should only be considered after drug-induced causes like **thiazides** are ruled out. - SIADH is often associated with specific triggers such as **malignancy, CNS disorders, or pulmonary disease**, which are not mentioned in this history. *Cerebral salt wasting* - This condition typically follows **neurosurgical procedures** or head trauma and is characterized by significant **hypovolaemia** due to renal salt wasting. - This patient is clinically **euvolaemic** with moist mucous membranes and stable blood pressure, making this diagnosis unlikely. *Primary polydipsia* - In primary polydipsia, the excessive intake of water leads to the excretion of large amounts of very dilute urine, reflected by a **low urine osmolality** (typically <100 mOsm/kg). - This patient has a **high urine osmolality** (445 mOsm/kg), indicating that her urine is inappropriately concentrated. *Adrenal insufficiency* - Primary adrenal insufficiency usually presents with **hypotension** and classic electrolyte abnormalities such as **hyperkalaemia**, which are absent here (potassium 4.2 mmol/L). - Patients with adrenal crisis are typically **hypovolaemic** and hemodynamically unstable, whereas this patient has a normal blood pressure of 138/82 mmHg.

Question 49: A 59-year-old man with CKD stage 4 (eGFR 22 mL/min/1.73m²) secondary to hypertensive nephropathy is reviewed in clinic. Blood tests show: haemoglobin 96 g/L, MCV 88 fL, ferritin 180 µg/L, transferrin saturation 22%, serum iron 8 µmol/L. He reports increasing fatigue affecting his daily activities. What is the most appropriate next step in managing his anaemia?

A. Commence oral ferrous sulfate 200mg three times daily
B. Arrange blood transfusion to target haemoglobin >110 g/L
C. Commence erythropoiesis-stimulating agent therapy
D. Arrange bone marrow biopsy to exclude myelodysplasia
E. Commence intravenous iron therapy (Correct Answer)

Explanation: ***Commence intravenous iron therapy*** - In patients with **CKD stage 4**, optimizing iron stores is the mandatory first step before initiating **Erythropoiesis-Stimulating Agents (ESAs)** to ensure efficacy. - **Intravenous iron** is preferred over oral routes in advanced CKD as it bypasses **hepcidin-mediated** absorption blocks and more effectively raises **ferritin** and **transferrin saturation (TSAT)**. *Commence oral ferrous sulfate 200mg three times daily* - **Oral iron** is often poorly tolerated due to gastrointestinal side effects and is frequently ineffective in stage 4 CKD due to high **hepcidin levels**. - Guidelines generally favor **IV iron** in non-dialysis CKD patients who cannot tolerate or fail to reach targets on oral therapy, or when rapid correction is needed. *Arrange blood transfusion to target haemoglobin >110 g/L* - **Blood transfusions** should be avoided in CKD patients unless there is acute instability or severe symptoms, as they increase the risk of **HLA sensitization**. - Sensitization can significantly complicate future **renal transplantation** prospects by making it harder to find a compatible donor. *Commence erythropoiesis-stimulating agent therapy* - While **ESA therapy** treats the erythropoietin deficiency of CKD, it should not be started until **iron deficiency** is fully addressed to prevent "functional" iron deficiency. - Starting an ESA without adequate iron often leads to a poor **haemoglobin response** and requires higher, potentially toxic doses of the drug. *Arrange bone marrow biopsy to exclude myelodysplasia* - A **bone marrow biopsy** is invasive and unnecessary here as the **normocytic anaemia** and biochemical profile are classic for **CKD-related anaemia**. - This procedure is reserved for cases where the cause of anaemia remains **unexplained** after thorough initial investigation or failure to respond to standard therapy.

Question 50: A 48-year-old man with no significant past medical history presents with a 4mm distal ureteric calculus causing mild hydronephrosis. He has mild flank discomfort but is systemically well with normal renal function (creatinine 82 µmol/L), no fever, and white cell count 7.2 × 10⁹/L. Stone analysis from a previous episode showed calcium oxalate composition. Which investigation would be most useful in identifying a metabolic cause for recurrent stone formation?

A. Serum calcium, phosphate, parathyroid hormone, and vitamin D levels
B. 24-hour urine collection for calcium, oxalate, citrate, uric acid, and volume (Correct Answer)
C. Fasting plasma glucose and HbA1c
D. Serum uric acid level
E. Urinary pH measurement on spot sample

Explanation: ***24-hour urine collection for calcium, oxalate, citrate, uric acid, and volume*** - This is the **gold standard** for identifying metabolic risk factors in patients with **recurrent stones**, allowing for the assessment of **hypercalciuria, hyperoxaluria, and hypocitraturia**. - It provides a comprehensive profile that guides specific medical and dietary interventions to prevent future **calcium oxalate** stone formation, which is the stone type this patient had previously. *Serum calcium, phosphate, parathyroid hormone, and vitamin D levels* - While these tests help screen for **primary hyperparathyroidism** and other bone-metabolism disorders, they do not identify other common metabolic causes like **hyperoxaluria** or **hypocitraturia**. - This assessment is narrower in scope than a 24-hour urine collection and is usually secondary or supplementary to a comprehensive urine metabolic profile in recurrent stone formers. *Fasting plasma glucose and HbA1c* - These tests screen for **diabetes mellitus**, which is associated with metabolic syndrome and an increased risk of uric acid stones or calcium stones, but they do not directly identify the specific metabolic imbalances leading to **calcium oxalate** stone formation. - They are not part of the standard initial **metabolic evaluation** for recurrent nephrolithiasis specifically targeting the urinary environment. *Serum uric acid level* - Serum uric acid levels do not reliably reflect **urinary uric acid excretion**, which is the relevant factor for uric acid stone formation or for promoting calcium oxalate stone formation. - Although elevated **uricosuria** can promote calcium oxalate stone formation by acting as a nidus, its assessment requires a 24-hour urine collection, not a spot serum test. *Urinary pH measurement on spot sample* - A spot urinary pH sample is highly variable depending on diet, hydration status, and time of day, making it unreliable for diagnosing chronic conditions like **renal tubular acidosis** or consistently acidic urine that promotes stone formation. - A **24-hour urine pH** measurement is required to accurately assess the overall urinary environment and detect persistent abnormalities that promote stone crystallization over a full cycle.

Question 51: A 66-year-old woman with CKD stage 3a presents with lethargy. Blood tests show: sodium 138 mmol/L, potassium 6.8 mmol/L, creatinine 168 µmol/L (baseline 145 µmol/L), bicarbonate 18 mmol/L, glucose 6.2 mmol/L. ECG shows tall tented T waves and prolonged PR interval. She takes ramipril, amlodipine, atorvastatin, and spironolactone. What is the most important immediate treatment?

A. Intravenous calcium gluconate 10ml of 10% solution (Correct Answer)
B. Intravenous insulin 10 units with 50ml of 50% dextrose
C. Oral calcium resonium 15g three times daily
D. Stop spironolactone and repeat potassium in 48 hours
E. Emergency haemodialysis

Explanation: ***Intravenous calcium gluconate 10ml of 10% solution*** - The patient presents with **severe hyperkalaemia** (6.8 mmol/L) and **ECG changes** (tall tented T waves, prolonged PR interval), necessitating immediate **cardiac membrane stabilization**. - Intravenous calcium gluconate acts rapidly to antagonize the myocardial effects of hyperkalaemia, preventing **life-threatening arrhythmias** without lowering serum potassium levels. *Intravenous insulin 10 units with 50ml of 50% dextrose* - This therapy is crucial for **shifting potassium intracellularly**, thereby lowering the serum potassium level. - However, its onset of action is slower than calcium, and it does not offer immediate protection against the **cardiac arrhythmogenic effects** seen on ECG, making it a subsequent step to cardiac stabilization. *Oral calcium resonium 15g three times daily* - **Calcium resonium** is a potassium-binding resin that works in the gastrointestinal tract to **remove potassium** from the body. - Its action is too **slow** (hours to days) for the emergent management of severe hyperkalaemia with ECG changes, which requires immediate intervention. *Stop spironolactone and repeat potassium in 48 hours* - Stopping **spironolactone** (and ramipril) is essential as they contribute to hyperkalaemia in CKD by impairing potassium excretion. - However, waiting 48 hours to reassess potassium is an unacceptably **delayed response** given the acute and dangerous cardiac manifestations, requiring immediate protective measures. *Emergency haemodialysis* - **Haemodialysis** is the most effective method for rapid and definitive **potassium removal** in patients with CKD and severe hyperkalaemia. - While indicated for this patient, it is not the *immediate* first step; **cardiac stabilization** with calcium gluconate must precede or accompany preparations for dialysis due to its rapid onset of action.

Question 52: A 41-year-old man with autosomal dominant polycystic kidney disease and CKD stage 4 presents with severe left-sided abdominal pain and visible haematuria. CT abdomen shows a large left renal cyst with high attenuation suggestive of acute haemorrhage. Blood pressure is 165/95 mmHg, haemoglobin is 118 g/L (baseline 125 g/L), and he is haemodynamically stable. What is the most appropriate initial management?

A. Emergency nephrectomy
B. Urgent CT angiography with selective renal artery embolization
C. Ultrasound-guided cyst aspiration and drainage
D. Conservative management with analgesia, bed rest, and blood pressure control (Correct Answer)
E. Urgent haemodialysis to correct uraemia

Explanation: ***Conservative management with analgesia, bed rest, and blood pressure control*** - Cyst **haemorrhage** is a common complication of **ADPKD** and is usually self-limiting, resolving within 2 to 7 days with supportive care. - This patient is **haemodynamically stable** with a minimal drop in hemoglobin, making **conservative management** the safest initial approach to preserve residual renal function. *Emergency nephrectomy* - **Nephrectomy** is a high-risk procedure reserved only for life-threatening, **uncontrolled haemorrhage** that fails all other interventions. - It would lead to the immediate loss of all **residual renal function**, which is critical to maintain in a patient with **CKD stage 4**. *Urgent CT angiography with selective renal artery embolization* - **Arterial embolization** is an invasive intervention reserved for patients who remain **haemodynamically unstable** or have persistent, severe bleeding. - Since the patient is currently stable, this step is premature and carries risks of **contrast-induced nephropathy** or further renal infarction. *Ultrasound-guided cyst aspiration and drainage* - Aspiration is generally avoided because it carries a significant risk of introducing bacteria and converting a **haemorrhagic cyst** into an **infected cyst** or abscess. - It does not address the underlying source of bleeding and is not the standard of care for acute **intracystic haemorrhage**. *Urgent haemodialysis to correct uraemia* - There is no clinical evidence provided of **symptomatic uraemia**, life-threatening hyperkalaemia, or fluid overload that would necessitate **urgent dialysis**. - While **uraemic platelet dysfunction** can contribute to bleeding, the primary management focuses on the anatomical source of the bleed in a stable patient.

Question 53: A 54-year-old man with type 2 diabetes and CKD stage 3b (eGFR 38 mL/min/1.73m²) is admitted with acute coronary syndrome. He undergoes emergency coronary angiography with stenting. Post-procedure, his creatinine rises from 145 µmol/L to 298 µmol/L over 48 hours. Urine output remains adequate at 1.2 mL/kg/hr. Which finding on urinalysis would be most consistent with contrast-induced nephropathy?

A. Muddy brown casts and epithelial cells
B. Hyaline casts with minimal proteinuria (Correct Answer)
C. Red cell casts and dysmorphic red blood cells
D. White cell casts and bacteria
E. Broad waxy casts and heavy proteinuria

Explanation: ***Hyaline casts with minimal proteinuria*** - **Contrast-induced nephropathy (CIN)** is frequently characterized by a relatively **bland urinary sediment**, where **hyaline casts** are the primary finding due to non-specific precipitation of Tamm-Horsfall protein. - Minimal proteinuria is expected as CIN primarily involves **tubular injury** and transient renal vasoconstriction rather than significant glomerular damage. *Muddy brown casts and epithelial cells* - These findings are classic for **acute tubular necrosis (ATN)**, often resulting from prolonged ischemia or more severe nephrotoxicity leading to sloughing of tubular cells. - While CIN is pathologically a form of ATN, its clinical presentation on urinalysis is often less dramatic and typically lacks the prominent muddy brown casts of severe ATN. *Red cell casts and dysmorphic red blood cells* - These markers are indicative of **glomerulonephritis** or renal vasculitis, suggesting damage to the **glomerular filtration barrier**. - They are not associated with the direct tubular toxicity or hemodynamics observed in contrast-mediated injury. *White cell casts and bacteria* - These findings are pathognomonic for **acute pyelonephritis** or severe urinary tract infections infiltrating the renal parenchyma. - **Contrast-induced AKI** is a sterile, chemical/ischemic process and does not typically involve infectious markers. *Broad waxy casts and heavy proteinuria* - **Broad waxy casts** signify advanced, **chronic kidney disease (CKD)** with dilated, atrophic tubules, while **heavy proteinuria** indicates significant glomerular damage. - While the patient has baseline CKD, these findings describe chronic, severe disease rather than the **acute changes** expected during an episode of contrast-induced injury.

Question 54: A 29-year-old woman presents with a 3-day history of dysuria and urinary frequency. She is sexually active and uses oral contraception. Urine dipstick shows leucocytes ++, nitrites +, blood +. Pregnancy test is negative. She has no fever and examination is unremarkable apart from mild suprapubic tenderness. She mentions she was treated for a UTI with trimethoprim 6 weeks ago. What is the most appropriate initial management?

A. Send urine for culture and await results before prescribing antibiotics
B. Prescribe nitrofurantoin 100mg modified-release twice daily for 3 days (Correct Answer)
C. Prescribe trimethoprim 200mg twice daily for 3 days
D. Prescribe pivmecillinam 400mg three times daily for 3 days
E. Prescribe ciprofloxacin 500mg twice daily for 7 days

Explanation: ***Prescribe nitrofurantoin 100mg modified-release twice daily for 3 days***- This patient presents with an **uncomplicated lower urinary tract infection (UTI)**, and **nitrofurantoin** is a recommended first-line empirical choice.- Since she was treated with **trimethoprim 6 weeks ago**, choosing a different class like nitrofurantoin minimizes the risk of **antibiotic resistance**.*Send urine for culture and await results before prescribing antibiotics*- Empirical treatment is recommended for symptomatic women with positive **urine dipstick** findings (nitrites/leucocytes) rather than delaying care for cultures.- Cultures are generally reserved for **recurrent UTIs**, pregnancy, or cases where empirical treatment fails.*Prescribe trimethoprim 200mg twice daily for 3 days*- Recent use of **trimethoprim** within the last 3-6 months significantly increases the risk of **bacterial resistance** to this specific drug.- Guidelines suggest avoiding the same antibiotic class if a person has been treated for a UTI in the preceding **3 months**.*Prescribe pivmecillinam 400mg three times daily for 3 days*- While **pivmecillinam** is a valid alternative, nitrofurantoin is more frequently utilized as the primary first-line agent in many UK-based protocols.- Given the options, **nitrofurantoin** modified-release is the standard preferred choice for a non-pregnant woman with no renal impairment.*Prescribe ciprofloxacin 500mg twice daily for 7 days*- Fluoroquinolones like **ciprofloxacin** are reserved for **pyelonephritis** or complicated UTIs and are not first-line for simple cystitis due to side effect profiles.- Using a 7-day course and broad-spectrum agents for uncomplicated cases promotes **antimicrobial resistance** and risk of **C. difficile**.

Question 55: A 34-year-old woman with systemic lupus erythematosus develops acute kidney injury. Renal biopsy shows Class IV proliferative lupus nephritis with cellular crescents in 45% of glomeruli. She has normal cardiac and respiratory function. Which induction immunosuppression regimen is most appropriate for this patient?

A. High-dose oral prednisolone alone
B. Mycophenolate mofetil with corticosteroids (Correct Answer)
C. Azathioprine with corticosteroids
D. Ciclosporin with corticosteroids
E. Rituximab monotherapy

Explanation: ***Mycophenolate mofetil with corticosteroids***- The patient has **Class IV proliferative lupus nephritis with cellular crescents**, a severe form requiring potent induction therapy. **Mycophenolate mofetil (MMF)** combined with **corticosteroids** is a preferred first-line induction regimen for this condition.- MMF is effective in inducing remission and is often favored in younger patients due to a **better safety profile** and lower risk of infertility compared to cyclophosphamide.*High-dose oral prednisolone alone*- **Corticosteroid monotherapy** is insufficient for severe, **proliferative lupus nephritis** like Class IV with crescents, which requires more potent immunosuppression.- Relying solely on steroids would inadequately control the **active inflammation and cellular proliferation**, leading to poor renal outcomes.*Azathioprine with corticosteroids*- **Azathioprine** is generally considered less potent than MMF or cyclophosphamide for the **induction of remission** in severe proliferative lupus nephritis.- It is primarily used as a **maintenance therapy** after remission has been induced, rather than for initial aggressive induction.*Ciclosporin with corticosteroids*- **Calcineurin inhibitors (CNIs)** like ciclosporin are not standard first-line induction agents for **proliferative (Class IV) lupus nephritis**, especially with crescentic features.- While CNIs can help with proteinuria, they are less effective at controlling the underlying **proliferative and inflammatory lesions** than MMF or cyclophosphamide.*Rituximab monotherapy*- **Rituximab** is not recommended as **monotherapy** for the initial induction of severe lupus nephritis.- Its use is typically reserved for **refractory cases** that do not respond to conventional induction regimens or when other agents are contraindicated.

Question 56: A 62-year-old man with poorly controlled type 2 diabetes presents with sudden onset left flank pain radiating to the groin. CT KUB confirms a 7mm calculus in the left proximal ureter with moderate hydronephrosis. Blood tests show creatinine 156 µmol/L (baseline 98 µmol/L), white cell count 14.2 × 10⁹/L, CRP 95 mg/L, and temperature 38.8°C. Urine culture is pending. What is the most appropriate immediate management?

A. Emergency lithotripsy within 24 hours
B. Urgent nephrostomy or ureteric stent insertion (Correct Answer)
C. Intravenous fluids, analgesia, and antibiotics with admission for observation
D. Alpha-blocker therapy and outpatient follow-up in 2 weeks
E. Immediate percutaneous nephrolithotomy

Explanation: ***Urgent nephrostomy or ureteric stent insertion***- This patient has **obstructive pyelonephritis** (infected hydronephrosis), evidenced by a stone, **fever**, **leukocytosis**, elevated **CRP**, and acute kidney injury, which is a urological emergency.- Immediate **decompression** of the collecting system via nephrostomy or stenting is vital to relieve the obstruction and prevent **urosepsis** and irreversible **renal damage**.*Emergency lithotripsy within 24 hours*- **Extracorporeal shock wave lithotripsy (ESWL)** is absolutely contraindicated in the presence of an active urinary tract infection or **sepsis** as it can worsen the infection and precipitate septic shock.- The immediate priority for an infected obstructed kidney is **drainage**, not definitive stone fragmentation.*Intravenous fluids, analgesia, and antibiotics with admission for observation*- While **intravenous fluids**, **analgesia**, and **antibiotics** are crucial supportive treatments, they are **insufficient** as standalone management in an infected obstructed kidney.- Failure to **drain the infected urine** behind the stone will lead to antibiotic failure, clinical deterioration, and potentially **septic shock**.*Alpha-blocker therapy and outpatient follow-up in 2 weeks*- **Alpha-blocker therapy (Medical Expulsive Therapy)** is suitable only for uncomplicated, smaller ureteral stones, typically in the absence of infection or significant renal compromise.- This patient's clinical presentation with **fever**, **AKI**, and systemic inflammation mandates urgent inpatient intervention and **drainage**, not outpatient management.*Immediate percutaneous nephrolithotomy*- **Percutaneous nephrolithotomy (PCNL)** is a definitive surgical procedure for stone removal but is generally **contraindicated** during an acute septic episode due to increased risks of bleeding and bacterial dissemination.- The immediate goal is **drainage** and patient stabilization; definitive stone removal is typically deferred until the infection is controlled and the patient is stable.

Question 57: A 44-year-old man with chronic kidney disease is started on cinacalcet by the renal team. His recent blood tests showed corrected calcium 2.75 mmol/L, phosphate 1.95 mmol/L, parathyroid hormone 85 pmol/L (reference range 1.6-6.9), and eGFR 18 mL/min/1.73m². Which mechanism best describes how cinacalcet works in managing this patient's condition?

A. Inhibits 1-alpha-hydroxylase in the kidney to reduce active vitamin D synthesis
B. Increases sensitivity of calcium-sensing receptors on parathyroid glands (Correct Answer)
C. Binds dietary phosphate in the gastrointestinal tract to reduce absorption
D. Competitively inhibits parathyroid hormone receptors in bone and kidney
E. Directly suppresses parathyroid gland chief cell proliferation

Explanation: ***Increases sensitivity of calcium-sensing receptors on parathyroid glands***- **Cinacalcet** is a **calcimimetic** agent that works by allosterically modulating the **calcium-sensing receptor (CaSR)** on the parathyroid glands.- By making the parathyroid glands 'think' there is more calcium present, it effectively **suppresses PTH secretion**, thereby lowering elevated PTH levels in conditions like **secondary hyperparathyroidism** found in CKD. *Inhibits 1-alpha-hydroxylase in the kidney to reduce active vitamin D synthesis*- This mechanism would reduce the production of **calcitriol** (active vitamin D), which is counterproductive in CKD patients who already have impaired **1-alpha-hydroxylase** activity.- Cinacalcet does not affect vitamin D synthesis; its action is directly on the **parathyroid gland's CaSR**. *Binds dietary phosphate in the gastrointestinal tract to reduce absorption*- This describes the action of **phosphate binders** (e.g., sevelamer, calcium acetate), which are used to manage **hyperphosphatemia** in CKD.- Cinacalcet has no direct effect on phosphate absorption in the **gastrointestinal tract**. *Competitively inhibits parathyroid hormone receptors in bone and kidney*- Cinacalcet's action is on the **parathyroid gland** itself to reduce PTH production, not on the peripheral **PTH receptors** in bone or kidney.- There are no approved drugs that act as competitive **PTH receptor antagonists** for this indication. *Directly suppresses parathyroid gland chief cell proliferation*- While long-term control of PTH may indirectly reduce parathyroid gland hyperplasia, cinacalcet's primary mechanism is **functional modulation** of existing CaSRs, not direct **anti-proliferative** effects.- **Vitamin D analogues** are known to have direct effects on suppressing parathyroid cell proliferation and PTH gene expression.

Question 58: A 58-year-old woman is admitted with community-acquired pneumonia. Her admission serum creatinine is 95 µmol/L. She is treated with intravenous co-amoxiclav and clarithromycin. On day 3, her creatinine rises to 245 µmol/L. Urine output is 0.3 mL/kg/hr. Examination reveals temperature 38.2°C, blood pressure 105/65 mmHg, and bilateral crepitations. Urinalysis shows blood ++, protein +, no leucocytes or nitrites. Which stage of acute kidney injury does this patient have according to the KDIGO criteria?

A. Stage 1
B. Stage 2 (Correct Answer)
C. Stage 3
D. No AKI present
E. Cannot be classified without 48-hour creatinine trend

Explanation: ***Stage 2*** - According to **KDIGO criteria**, Stage 2 AKI is defined by a serum creatinine increase of **2.0 to 2.9 times** the baseline value within 7 days, or an absolute increase of **2.0 to 2.9 times** within 48 hours. - The patient's creatinine rose from 95 µmol/L to 245 µmol/L, which is approximately **2.58 times the baseline**, clearly falling within the **Stage 2** classification. *Stage 1* - This stage requires a creatinine rise of **1.5 to 1.9 times** baseline or an absolute increase of ≥26.5 µmol/L (0.3 mg/dL) within 48 hours. - The patient's creatinine rise of 2.58 times baseline significantly exceeds the threshold for Stage 1, indicating a more severe injury. *Stage 3* - Requires a creatinine rise of **≥3.0 times** baseline, an absolute value of **≥353.6 µmol/L** (4.0 mg/dL), or urine output **<0.3 mL/kg/hr for ≥24 hours**. - While the urine output is 0.3 mL/kg/hr, the duration is not specified to meet the 24-hour criterion for Stage 3, and the creatinine increase is below the 3.0x threshold. *No AKI present* - Acute Kidney Injury is clearly present as there is a sharp **rise in creatinine** from 95 to 245 µmol/L and a **reduction in urine output**. - The patient demonstrates clear clinical evidence of renal impairment, meeting the KDIGO criteria for AKI. *Cannot be classified without 48-hour creatinine trend* - KDIGO criteria allow classification based on a **baseline creatinine** comparison within a 7-day window or an absolute rise within 48 hours. - The significant rise from baseline (95 to 245 µmol/L) observed within 3 days of admission is sufficient to accurately determine the **KDIGO stage**.

Question 59: A 70-year-old man with ischaemic heart disease is found to have the following arterial blood gas on room air: pH 7.32, PaO2 11.2 kPa, PaCO2 4.8 kPa, HCO3- 16 mmol/L, base excess -8 mmol/L. His venous blood tests show: sodium 139 mmol/L, potassium 5.2 mmol/L, chloride 112 mmol/L, urea 18.5 mmol/L, creatinine 245 μmol/L, glucose 6.2 mmol/L, lactate 1.8 mmol/L. What is the most likely cause of his acid-base disturbance?

A. Normal anion gap metabolic acidosis secondary to renal tubular acidosis type 4 (Correct Answer)
B. Normal anion gap metabolic acidosis secondary to diarrhoea
C. High anion gap metabolic acidosis secondary to uraemic acidosis
D. High anion gap metabolic acidosis secondary to lactic acidosis
E. Mixed metabolic acidosis with respiratory compensation

Explanation: ***Normal anion gap metabolic acidosis secondary to renal tubular acidosis type 4***- The calculated **anion gap** is 11 mmol/L ([139] - [112 + 16]), which is within the normal range, indicating a **normal anion gap metabolic acidosis (NAGMA)**.- This patient's **chronic kidney disease** (creatinine 245 μmol/L) and **hyperkalaemia** (K+ 5.2 mmol/L) are characteristic features of **Type 4 RTA**, which involves impaired aldosterone function leading to reduced H+ and K+ excretion.*Normal anion gap metabolic acidosis secondary to diarrhoea*- While **diarrhoea** can cause NAGMA due to bicarbonate loss from the GI tract, it typically leads to **hypokalaemia**, which contradicts the hyperkalaemia observed here.- There is no clinical information provided to suggest significant **gastrointestinal bicarbonate losses** in this patient.*High anion gap metabolic acidosis secondary to uraemic acidosis*- **Uraemic acidosis**, a common complication of advanced renal failure, typically presents as a **high anion gap metabolic acidosis (HAGMA)** due to the accumulation of unmeasured organic acids.- The calculated **anion gap** of 11 mmol/L falls within the normal range, thereby ruling out a primary HAGMA.*High anion gap metabolic acidosis secondary to lactic acidosis*- The patient's **serum lactate** of 1.8 mmol/L is within the **normal range** (< 2 mmol/L), which effectively excludes lactic acidosis as the primary cause.- **Lactic acidosis** would also present as a **high anion gap metabolic acidosis**, which is not consistent with this patient's normal anion gap.*Mixed metabolic acidosis with respiratory compensation*- The patient's **PaCO2** of 4.8 kPa (approximately 36 mmHg) represents an **appropriate compensatory response** to the metabolic acidosis, as predicted by Winter's formula (expected PaCO2 ~32 mmHg for HCO3- of 16).- There is no evidence of an additional primary respiratory disturbance or other significant acid-base derangements beyond the single underlying **renal pathology**.

Question 60: A 32-year-old pregnant woman at 30 weeks gestation presents with fever, rigors, right loin pain, and vomiting. Temperature is 38.8°C, BP 108/68 mmHg, pulse 108 bpm. Urine dipstick shows: leucocytes +++, nitrites ++, blood +. She appears clinically dehydrated. Blood tests show: WCC 16.5 × 10⁹/L, CRP 185 mg/L, creatinine 98 μmol/L. What is the most appropriate antibiotic therapy?

A. Intravenous cefuroxime (Correct Answer)
B. Intravenous gentamicin
C. Oral trimethoprim for 14 days
D. Oral ciprofloxacin for 7 days
E. Oral nitrofurantoin for 7 days

Explanation: ***Intravenous cefuroxime*** - This patient presents with systematic signs of **acute pyelonephritis** in pregnancy, which requires hospitalization and **intravenous broad-spectrum antibiotics** like second-generation cephalosporins. - **Cefuroxime** is safe in pregnancy and effectively covers common causative organisms like **E. coli** while achieving high tissue concentrations in the kidneys. *Intravenous gentamicin* - While highly effective against Gram-negative bacteria, it is generally avoided in pregnancy due to the risk of **fetal ototoxicity** and **nephrotoxicity**. - It is reserved for severe **multi-drug resistant sepsis** where no safer alternatives are available under close monitoring. *Oral trimethoprim for 14 days* - **Trimethoprim** is a folate antagonist and is contraindicated in the **first trimester**, but even in the third trimester, it is not the first-line choice for severe, systemic pyelonephritis. - Oral therapy is inappropriate for this patient as she is clinical dehydrated and **vomiting**, requiring initial stabilization with IV fluids and medications. *Oral ciprofloxacin for 7 days* - **Quinolones** such as ciprofloxacin are generally contraindicated throughout pregnancy due to concerns regarding **fetal arthropathy** and damage to developing **cartilage**. - Oral therapy is insufficient for a patient presenting with high fever, rigors, and vomiting, suggesting a risk of **urosepsis**. *Oral nitrofurantoin for 7 days* - **Nitrofurantoin** is contraindicated near term (after 36 weeks) due to the risk of **neonatal haemolysis**, but more importantly, it only concentrates in the urine. - It is effective for **uncomplicated cystitis** but reaches inadequate levels in the **renal parenchyma** and bloodstream to treat pyelonephritis.

Question 61: A 38-year-old woman presents to the emergency department with severe generalized weakness. She reports 5 days of profuse watery diarrhoea. Blood tests reveal: sodium 138 mmol/L, potassium 2.1 mmol/L, chloride 95 mmol/L, bicarbonate 32 mmol/L, urea 8.2 mmol/L, creatinine 95 μmol/L, magnesium 0.55 mmol/L. ECG shows flattened T waves, prominent U waves, and prolonged QT interval. What is the most appropriate initial management?

A. Oral potassium supplementation 24 mmol three times daily
B. Intravenous calcium gluconate followed by potassium replacement
C. Intravenous potassium chloride infusion without magnesium supplementation
D. Immediate haemodialysis
E. Intravenous potassium chloride infusion with cardiac monitoring, and intravenous magnesium replacement (Correct Answer)

Explanation: ***Intravenous potassium chloride infusion with cardiac monitoring, and intravenous magnesium replacement*** - The patient has **severe hypokalaemia** (2.1 mmol/L) with **cardiac manifestations** (flattened T waves, prominent U waves, prolonged QT interval), necessitating urgent **intravenous replacement** and continuous **ECG monitoring** due to the high risk of arrhythmias. - Concurrent **hypomagnesaemia** (0.55 mmol/L) must be corrected simultaneously, as magnesium is a necessary cofactor for **renal potassium reabsorption**; without it, potassium wasting continues and hypokalaemia becomes **refractory to treatment**.*Oral potassium supplementation 24 mmol three times daily* - **Oral replacement** is inadequate and too slow for **severe hypokalaemia** (<2.5 mmol/L) or when **ECG changes** are present, as it does not raise serum levels rapidly enough to mitigate life-threatening arrhythmia risk. - This approach also fails to address the significant **magnesium deficiency**, which is crucial for effective potassium repletion and preventing ongoing renal potassium losses.*Intravenous calcium gluconate followed by potassium replacement* - **Calcium gluconate** is indicated for immediate myocardial stabilization in **hyperkalaemia**, not hypokalaemia, and has no role in treating low potassium or magnesium levels. - While potassium replacement is needed, starting with calcium gluconate is inappropriate and could potentially worsen certain cardiac rhythms in a hypokalaemic state.*Intravenous potassium chloride infusion without magnesium supplementation* - Administering potassium alone in the presence of **hypomagnesaemia** is often **ineffective** because magnesium deficiency leads to increased **renal potassium excretion** via the ROMK channels in the distal tubule. - Failure to correct magnesium simultaneously increases the risk of **persistent hypokalaemia**, ongoing cardiac arrhythmias, and makes the potassium repletion attempt inefficient.*Immediate haemodialysis* - **Haemodialysis** is an emergent treatment for severe **hyperkalaemia**, refractory fluid overload, or acute renal failure, where the goal is to remove substances from the blood. - In this case, the patient is experiencing electrolyte *deficits* (hypokalaemia, hypomagnesaemia) due to severe diarrhoea, requiring **replacement** rather than removal.

Question 62: A 52-year-old woman with type 1 diabetes for 30 years attends her annual diabetic review. Her blood pressure is 142/88 mmHg. Blood tests show: HbA1c 68 mmol/mol (8.4%), creatinine 115 μmol/L (eGFR 48 mL/min/1.73m²), potassium 4.5 mmol/L. Urine albumin:creatinine ratio is 28 mg/mmol (previous result 6 months ago was 26 mg/mmol). What is the classification of her chronic kidney disease?

A. CKD G3bA3
B. CKD G3aA3 (Correct Answer)
C. CKD G3aA2
D. CKD G2A2
E. CKD G3aA1

Explanation: ***CKD G3aA2*** (Note: The provided answer key in the source prompt suggests G3aA3, but technically 26-28 mg/mmol falls under category A2). - The patient's **eGFR is 48 mL/min/1.73m²**, which falls specifically into the **G3a category** (45–59 mL/min/1.73m²). - Her persistent **Urine Albumin:Creatinine Ratio (ACR)** of 28 mg/mmol is within the 3–30 mg/mmol range, defined as **category A2** (moderately increased albuminuria). *CKD G3bA3* - Category **G3b** requires an eGFR between 30–44 mL/min/1.73m², which is lower than this patient's calculated value. - Category **A3** (severely increased albuminuria) is defined by an ACR of **>30 mg/mmol**. *CKD G3aA3* - While the GFR category is correct, the patient's ACR of 28 mg/mmol does not meet the **A3 threshold** of >30 mg/mmol. - This stage would signify a higher risk of **progression to end-stage renal disease** than what her current labs indicate. *CKD G2A2* - Category **G2** is defined by an eGFR of 60–89 mL/min/1.73m², which indicates much better renal function than her eGFR of 48. - This classification would underestimate the severity of her **diabetic nephropathy**. *CKD G3aA1* - Category **A1** is defined as an ACR of **<3 mg/mmol**, representing normal to mildly increased albuminuria. - With an ACR of 28 mg/mmol, she has significant **microalbuminuria**, placing her well above the A1 cutoff.

Question 63: A 76-year-old man with benign prostatic hyperplasia presents with a 6-hour history of inability to pass urine and severe suprapubic pain. On examination, there is a palpable bladder reaching to the umbilicus. Urethral catheterization is attempted but fails. His observations are stable. What is the most appropriate next step in management?

A. Intravenous furosemide to promote diuresis
B. Repeated attempts at urethral catheterization with different sized catheters
C. Suprapubic catheter insertion (Correct Answer)
D. Urgent transurethral resection of prostate
E. Trial of tamsulosin and wait for spontaneous voiding

Explanation: ***Suprapubic catheter insertion***- When **urethral catheterization fails** in a patient with **acute urinary retention**, a suprapubic catheter is the gold standard for immediate **bladder decompression**.- This procedure provides rapid symptomatic relief and prevents complications like **obstructive uropathy** or bladder wall ischemia without further traumatizing the urethra.*Intravenous furosemide to promote diuresis*- Administering a **loop diuretic** is contraindicated here as it would increase urine production and worsen the **suprapubic pain** and bladder distension.- It does nothing to resolve the **anatomical or functional obstruction** caused by the benign prostatic hyperplasia.*Repeated attempts at urethral catheterization with different sized catheters*- Multiple failed attempts increase the risk of **urethral trauma**, significant bleeding, and the creation of a **false passage**.- Persistence is discouraged after initial failure by an experienced clinician; alternative drainage methods must be sought to avoid permanent **urethral strictures**.*Urgent transurethral resection of prostate*- **TURP** is a definitive surgical treatment for BPH but is not performed as an **emergency procedure** during a state of acute retention.- The primary goal in the acute setting is **bladder drainage** and patient stabilization, with surgery considered only after a formal workup.*Trial of tamsulosin and wait for spontaneous voiding*- **Alpha-blockers** like tamsulosin take time to work and are used to facilitate a **Trial Without Catheter (TWOC)** only after the bladder has been successfully drained.- Leaving a patient in acute retention while waiting for medication to take effect is inappropriate and risks **renal failure** and severe distress.

Question 64: A 67-year-old woman presents with progressive ankle swelling and frothy urine. Blood tests reveal: creatinine 98 μmol/L, albumin 18 g/L, cholesterol 9.2 mmol/L, triglycerides 4.5 mmol/L. Urine protein:creatinine ratio is 520 mg/mmol. Renal biopsy shows thickened glomerular basement membrane with subepithelial deposits on electron microscopy and positive anti-phospholipase A2 receptor antibodies. What is the most likely diagnosis?

A. Primary membranous nephropathy (Correct Answer)
B. Minimal change disease
C. Focal segmental glomerulosclerosis
D. IgA nephropathy
E. Membranoproliferative glomerulonephritis

Explanation: ***Primary membranous nephropathy*** - The presence of **anti-phospholipase A2 receptor (PLA2R) antibodies** is highly specific for the primary form of this disease and is a definitive diagnostic marker. - Histology showing **thickened glomerular basement membrane** and **subepithelial deposits** on electron microscopy confirms this diagnosis in the context of nephrotic syndrome. *Minimal change disease* - This condition typically shows **normal light microscopy** and only displays **podocyte foot process effacement** on electron microscopy. - It is the most common cause of nephrotic syndrome in **children**, whereas this patient is an older adult. *Focal segmental glomerulosclerosis* - Biopsy would reveal **segmental sclerosis** (scarring) in some, but not all, glomeruli rather than uniform membrane thickening. - It is not associated with **anti-PLA2R antibodies**, which are the hallmark of primary membranous disease. *IgA nephropathy* - Typically presents with **synpharyngitic macroscopic haematuria** (nephritic syndrome) rather than full-blown nephrotic syndrome with massive proteinuria. - Diagnosis requires **immunofluorescence** showing **IgA deposits** in the mesangium, not subepithelial deposits. *Membranoproliferative glomerulonephritis* - Characterized by **mesangial hypercellularity** and a **"tram-track" appearance** due to duplication of the glomerular basement membrane. - It often presents with a mixed **nephritic/nephrotic picture** and is frequently associated with low complement levels or chronic infections like Hepatitis C.

Question 65: A 58-year-old man with chronic kidney disease stage 5 (eGFR 12 mL/min/1.73m²) secondary to diabetes is being prepared for renal replacement therapy. His blood tests show: haemoglobin 88 g/L, ferritin 450 μg/L, transferrin saturation 35%, calcium 2.15 mmol/L, phosphate 2.1 mmol/L, bicarbonate 18 mmol/L, potassium 5.2 mmol/L. Blood pressure is 168/95 mmHg on ramipril 10 mg and amlodipine 10 mg. What is the target haemoglobin range for erythropoiesis-stimulating agent (ESA) therapy in this patient?

A. 100-120 g/L (Correct Answer)
B. 110-130 g/L
C. 120-140 g/L
D. 90-110 g/L
E. 130-150 g/L

Explanation: ***100-120 g/L***- According to **NICE** and **KDIGO** guidelines, the target haemoglobin for patients with **Chronic Kidney Disease (CKD)** on ESA therapy is **100-120 g/L**.- This range balances the improvement of **quality of life** and symptoms while minimizing the risk of **cardiovascular complications** like stroke or thrombosis.*110-130 g/L*- This range is too high; clinical trials like **CHOIR** and **CREATE** showed that targeting these levels increases the risk of **hypertension** and **vascular access thrombosis**.- Targets above 120 g/L do not provide additional survival benefits and may correlate with a higher **mortality rate** in CKD patients.*120-140 g/L*- Aiming for near-normal haemoglobin levels in renal failure is discouraged as it significantly increases the risk of **malignancy progression** and **stroke**.- Large trials like **TREAT** demonstrated that targets in this range lead to a higher incidence of **cardiovascular events** in diabetic CKD patients.*90-110 g/L*- While the lower limit of 100 g/L is acceptable for initiation, a target range including 90 g/L is generally too low and may leave the patient with **hypoxic symptoms** and **reduced exercise tolerance**.- ESA therapy is typically initiated when haemoglobin falls below **100 g/L** to prevent the need for **blood transfusions**, but the target range for maintenance is higher to optimize patient well-being.*130-150 g/L*- This represents a **normal physiological range** for healthy adults but is dangerously high for patients with CKD receiving **ESA therapy**.- Attempting to reach these levels can cause blood **hyperviscosity**, making the patient highly susceptible to **thromboembolic events** and **increased mortality**.

Question 66: A 42-year-old woman with systemic lupus erythematosus presents with fatigue and ankle swelling. Blood tests show: creatinine 145 μmol/L, albumin 22 g/L, cholesterol 7.8 mmol/L. Urine protein:creatinine ratio is 450 mg/mmol. Renal biopsy shows diffuse proliferative glomerulonephritis (Class IV lupus nephritis) with active lesions. What is the most appropriate initial immunosuppressive therapy?

A. Intravenous cyclophosphamide or mycophenolate mofetil plus corticosteroids (Correct Answer)
B. Rituximab monotherapy
C. Oral prednisolone alone at high dose
D. Azathioprine plus low-dose corticosteroids
E. Ciclosporin plus hydroxychloroquine

Explanation: ***Intravenous cyclophosphamide or mycophenolate mofetil plus corticosteroids*** - The patient's presentation with **Class IV lupus nephritis** with **active lesions**, significant **proteinuria**, and signs of **nephrotic syndrome** (low albumin, high cholesterol, ankle swelling) indicates severe renal involvement requiring aggressive induction therapy. - Current guidelines (EULAR/ERA-EDTA, KDIGO) recommend **high-dose corticosteroids** combined with either **intravenous cyclophosphamide** or **mycophenolate mofetil (MMF)** as first-line induction agents for such severe disease to induce remission and preserve renal function. *Rituximab monotherapy* - **Rituximab** is generally reserved for **refractory lupus nephritis** or as an **add-on therapy** for patients who do not respond adequately to standard induction regimens, rather than as initial monotherapy. - Evidence does not support **rituximab monotherapy** as a superior initial induction strategy for severe **Class IV lupus nephritis** compared to established regimens. *Oral prednisolone alone at high dose* - While **corticosteroids** are essential for reducing inflammation in lupus nephritis, **high-dose prednisolone alone** is insufficient to achieve remission in aggressive **diffuse proliferative (Class IV)** disease. - Relying solely on **steroid monotherapy** for severe lupus nephritis significantly increases the risk of **treatment failure**, progressive renal damage, and steroid-related side effects without adequate disease control. *Azathioprine plus low-dose corticosteroids* - **Azathioprine** is a less potent immunosuppressant compared to cyclophosphamide or MMF and is primarily used as **maintenance therapy** for lupus nephritis after remission has been achieved. - It is **inadequate for initial induction therapy** in patients with active, severe **Class IV lupus nephritis** due to its slower onset of action and lower efficacy in controlling acute inflammation. *Ciclosporin plus hydroxychloroquine* - **Ciclosporin**, a calcineurin inhibitor, is often used for **Class V (membranous)** lupus nephritis, especially for proteinuria, or as an alternative in Class III/IV patients intolerant to other agents; it's not a primary choice for active proliferative lesions. - **Hydroxychloroquine** is a fundamental long-term medication for all SLE patients for disease control but is **not potent enough** to induce remission in severe **active Class IV lupus nephritis**.

Question 67: Which of the following medications should be temporarily discontinued in a patient presenting with acute kidney injury secondary to dehydration?

A. Ramipril, metformin, and ibuprofen (Correct Answer)
B. Bisoprolol, clopidogrel, and omeprazole
C. Levothyroxine, sertraline, and paracetamol
D. Amlodipine, atorvastatin, and aspirin
E. Warfarin, digoxin, and furosemide

Explanation: ***Ramipril, metformin, and ibuprofen*** - **ACE inhibitors** (Ramipril) and **NSAIDs** (Ibuprofen) worsen AKI by disrupting renal autoregulation: Ramipril reduces efferent arteriolar tone, decreasing **glomerular filtration pressure**, while Ibuprofen inhibits vasodilatory **prostaglandins**, leading to afferent arteriolar constriction and reduced renal blood flow. - **Metformin** is primarily renally cleared; in AKI, its accumulation significantly increases the risk of **lactic acidosis**, a severe metabolic complication, necessitating temporary discontinuation. *Bisoprolol, clopidogrel, and omeprazole* - **Beta-blockers** like Bisoprolol are generally not nephrotoxic and can be continued in AKI unless the patient is severely **hypotensive** or bradycardic. - **Clopidogrel** (antiplatelet) and **Omeprazole** (proton pump inhibitor) do not directly affect renal hemodynamics or function and are typically not withheld in AKI. *Levothyroxine, sertraline, and paracetamol* - **Levothyroxine** and **Sertraline** are not known to be nephrotoxic and do not exacerbate AKI secondary to dehydration, so their continuation is usually safe. - **Paracetamol** (acetaminophen) is a safe analgesic choice in patients with renal impairment as it does not impair renal prostaglandin synthesis like NSAIDs. *Amlodipine, atorvastatin, and aspirin* - **Calcium channel blockers** (Amlodipine) and **Statins** (Atorvastatin) are generally not harmful to the kidneys and do not require discontinuation in dehydration-induced AKI. - Low-dose **cardioprotective aspirin** is typically continued in AKI, as its systemic anti-inflammatory effects are minimal and do not significantly compromise renal function, unlike high-dose NSAIDs. *Warfarin, digoxin, and furosemide* - **Warfarin** does not cause AKI, but its monitoring may need adjustment; **Digoxin** requires dose reduction in AKI due to renal excretion but is not always discontinued. - While **furosemide** (a diuretic) should be stopped in dehydration to prevent further volume depletion, this option is less comprehensive than the 'sick day rules' medications (ACEI, NSAIDs, Metformin) in the correct option.

Question 68: A 35-year-old man presents to the emergency department with sudden onset severe left-sided loin to groin pain. CT KUB confirms a 4 mm stone in the left distal ureter with mild hydronephrosis. He is afebrile with normal observations apart from pain. Creatinine is 82 μmol/L. He has been given diclofenac 75 mg IM with good pain relief. What is the most appropriate ongoing management advice?

A. Medical expulsive therapy with tamsulosin 400 micrograms once daily (Correct Answer)
B. Urgent ureteroscopy within 48 hours
C. Extracorporeal shockwave lithotripsy within 1 week
D. Admit for intravenous antibiotics and observation
E. Percutaneous nephrolithotomy within 2 weeks

Explanation: ***Medical expulsive therapy with tamsulosin 400 micrograms once daily*** - In patients with an uncomplicated **distal ureteric stone <5 mm** and no signs of infection or acute renal failure, **medical expulsive therapy (MET)** with an alpha-blocker is the most appropriate first-line management.- **Tamsulosin**, an alpha-blocker, works by relaxing the smooth muscle in the distal ureter, thereby facilitating **spontaneous stone passage** and reducing pain. *Urgent ureteroscopy within 48 hours* - **Ureteroscopy** is an invasive procedure typically reserved for larger stones (generally **>10 mm**), stones resistant to MET, or cases with complications like severe hydronephrosis, infection, or uncontrolled pain.- This patient has a **small 4 mm stone** and is clinically stable with good pain control, making urgent ureteroscopy an overaggressive initial approach. *Extracorporeal shockwave lithotripsy within 1 week* - **Extracorporeal shockwave lithotripsy (ESWL)** is a non-invasive procedure used for certain kidney and ureteric stones, but it is typically not the **initial management** for a small, uncomplicated distal ureteric stone.- For a 4 mm stone, the probability of spontaneous passage with MET is high, making conservative treatment preferable before considering ESWL. *Admit for intravenous antibiotics and observation* - **Admission for intravenous antibiotics** is primarily indicated in cases of **obstructed pyelonephritis** or **urosepsis**, evidenced by fever, leukocytosis, or other signs of infection along with obstruction.- This patient is **afebrile** with normal observations and a normal creatinine, indicating no acute infection or renal compromise requiring hospital admission or IV antibiotics. *Percutaneous nephrolithotomy within 2 weeks* - **Percutaneous nephrolithotomy (PCNL)** is a major surgical intervention reserved for very **large renal stones** (typically **>20 mm**) or complex **staghorn calculi**.- It is an inappropriate and overly invasive procedure for a **4 mm distal ureteric stone** which has a high chance of spontaneous passage or management with less invasive methods.

Question 69: A 45-year-old man with autosomal dominant polycystic kidney disease and chronic kidney disease stage 3b (eGFR 38 mL/min/1.73m²) presents with severe right-sided loin pain radiating to the groin. CT KUB shows a 7 mm calculus in the right mid-ureter with moderate hydronephrosis. His observations are: temperature 38.2°C, BP 145/88 mmHg, pulse 98 bpm. Blood tests show: WCC 15.2 × 10⁹/L, neutrophils 12.8 × 10⁹/L, CRP 145 mg/L, creatinine 195 μmol/L (baseline 155 μmol/L). What is the most appropriate management?

A. Urgent urological referral for nephrostomy or ureteric stenting within 24 hours (Correct Answer)
B. Analgesia and medical expulsive therapy with tamsulosin
C. Immediate emergency ureteroscopy and stone extraction
D. Intravenous antibiotics and elective stone treatment in 2-4 weeks
E. Extracorporeal shockwave lithotripsy (ESWL) within 48 hours

Explanation: ***Urgent urological referral for nephrostomy or ureteric stenting within 24 hours***- This patient presents with an **obstructed infected kidney** (obstructive pyelonephritis), evidenced by a stone, **fever (38.2°C)**, high CRP/WCC, and worsening renal function.- This is a **urological emergency** that requires urgent **surgical decompression** via nephrostomy or stenting to prevent sepsis and irreversible kidney damage.*Analgesia and medical expulsive therapy with tamsulosin*- Conservative management is only suitable for small, **uncomplicated stones** in patients who are hemodynamically stable and without infection.- Medical expulsive therapy is contraindicated here due to the presence of **systemic infection** and acute kidney injury.*Immediate emergency ureteroscopy and stone extraction*- Performing primary ureteroscopy in the presence of active infection is dangerous as it can trigger **life-threatening sepsis** by pushing bacteria into the bloodstream.- The priority is **drainage** first; definitive stone removal should only be performed once the patient is stable and the infection has cleared.*Intravenous antibiotics and elective stone treatment in 2-4 weeks*- Antibiotics alone cannot penetrate an **obstructed system** effectively and will fail to resolve the underlying source of infection.- Delaying decompression in the setting of **obstructive pyelonephritis** significantly increases the risk of mortality and severe renal failure.*Extracorporeal shockwave lithotripsy (ESWL) within 48 hours*- ESWL is contraindicated in the presence of an **active urinary tract infection** and is not the treatment of choice for an obstructing ureteric stone with sepsis.- In patients with **ADPKD**, ESWL carries additional risks such as the potential rupture of renal cysts and perinephric hematoma.

Question 70: A 28-year-old woman presents to her GP with a 2-day history of dysuria, urinary frequency, and suprapubic discomfort. She is otherwise well with no fever or loin pain. She is not pregnant and has no significant past medical history. Urine dipstick shows: leucocytes ++, nitrites +, blood +, protein trace. What is the most appropriate management according to current UK guidelines?

A. Send urine for microscopy, culture and sensitivity before treatment
B. Prescribe trimethoprim 200 mg twice daily for 3 days
C. Prescribe nitrofurantoin 100 mg modified-release twice daily for 3 days (Correct Answer)
D. Prescribe ciprofloxacin 500 mg twice daily for 7 days
E. Advise increased fluid intake and simple analgesia only

Explanation: ***Prescribe nitrofurantoin 100 mg modified-release twice daily for 3 days*** - In the UK, **nitrofurantoin** is the recommended first-line empirical treatment for **uncomplicated lower urinary tract infections (UTI)** in non-pregnant women due to low resistance rates of E. coli. - A **3-day course** is sufficient for acute cystitis in women, providing a balance between clinical cure and minimizing potential side effects. *Send urine for microscopy, culture and sensitivity before treatment* - Routine **urine culture** is not indicated for non-pregnant women with **uncomplicated cystitis** and a positive dipstick; it is reserved for treatment failure, pregnancy, or suspected pyelonephritis. - Management can be initiated based on **symptoms and dipstick** (positive nitrites and leucocytes) to avoid unnecessary delays and costs. *Prescribe trimethoprim 200 mg twice daily for 3 days* - While previously a first-line option, **trimethoprim** is now generally considered second-line or an alternative if there is a **low risk of resistance** (e.g., previous culture indicates sensitivity). - High rates of **bacterial resistance** to trimethoprim in many UK regions make nitrofurantoin the preferred choice for empirical therapy. *Prescribe ciprofloxacin 500 mg twice daily for 7 days* - **Fluoroquinolones** like ciprofloxacin should be avoided in uncomplicated UTIs due to significant **side effects** (tendonitis/aortic aneurysm) and antimicrobial stewardship concerns. - This agent is reserved for **complicated UTIs**, acute **pyelonephritis**, or cases where other antibiotics are not suitable. *Advise increased fluid intake and simple analgesia only* - Although **self-care advice** is a helpful adjunct, antibiotics are indicated here because the patient is symptomatic with a **positive dipstick** (leucocytes and nitrites). - Delayed prescribing may be considered for mild symptoms, but standard practice for clear acute **cystitis** is a short-course antibiotic to reduce morbidity.

Question 71: A 72-year-old man presents with confusion and lethargy. He has a history of small cell lung cancer currently receiving chemotherapy. Blood tests reveal: sodium 115 mmol/L, potassium 4.2 mmol/L, urea 3.5 mmol/L, creatinine 78 μmol/L, glucose 5.2 mmol/L, serum osmolality 240 mOsm/kg, urine sodium 45 mmol/L, urine osmolality 420 mOsm/kg. Clinically, he appears euvolaemic with no oedema. Thyroid and adrenal function are normal. What is the most appropriate initial management?

A. Intravenous 0.9% sodium chloride infusion
B. Oral water restriction to 500-750 mL per day (Correct Answer)
C. Intravenous 3% hypertonic saline infusion
D. Oral sodium chloride tablets 3 g three times daily
E. Intravenous furosemide 40 mg

Explanation: ***Oral water restriction to 500-750 mL per day*** - This patient presents with **SIADH** (euvolaemic hypotonic hyponatraemia with concentrated urine) secondary to **small cell lung cancer**, and **fluid restriction** is the first-line treatment for asymptomatic or mildly symptomatic cases. - Reducing fluid intake creates a negative water balance, allowing the **serum sodium** to rise gradually and safely without the risk of overcorrection. *Intravenous 0.9% sodium chloride infusion* - In **SIADH**, the kidneys excrete the salt from the saline while retaining the water due to high **ADH levels**, which can paradoxically worsen the hyponatraemia. - Isotonic saline is primarily indicated for **hypovolaemic hyponatraemia**, which is ruled out here by the patient's **euvolaemic** status. *Intravenous 3% hypertonic saline infusion* - While the sodium level is very low (115 mmol/L), hypertonic saline is typically reserved for **acute/severe symptoms** such as seizures, coma, or respiratory distress. - Rapid correction with hypertonic saline in chronic cases carries a high risk of **osmotic demyelination syndrome** (central pontine myelinolysis). *Oral sodium chloride tablets 3 g three times daily* - Sodium tablets are sometimes used as a second-line or adjunct treatment in chronic SIADH but are not the **initial management** of choice. - Without concomitant **fluid restriction**, the extra salt intake may be negated by the continued water retention driven by inappropriate ADH. *Intravenous furosemide 40 mg* - **Furosemide** may be used to increase free water clearance by interfering with the medullary concentration gradient, but it is not used as a standalone initial therapy for SIADH. - It is generally considered only if fluid restriction fails or as an adjunct to **hypertonic saline** in emergency settings to prevent volume overload.

Question 72: A 55-year-old woman with chronic kidney disease stage 4 (eGFR 22 mL/min/1.73m²) attends her nephrology clinic appointment. Her recent blood tests show: haemoglobin 95 g/L, ferritin 180 μg/L, transferrin saturation 25%, calcium 2.05 mmol/L, phosphate 1.95 mmol/L, PTH 15.2 pmol/L (normal range 1.6-6.9), vitamin D 35 nmol/L. She has no symptoms. Which complication of chronic kidney disease requires the most urgent treatment intervention?

A. Secondary hyperparathyroidism (Correct Answer)
B. Renal anaemia
C. Vitamin D deficiency
D. Hypocalcaemia
E. Hyperphosphataemia

Explanation: ***Secondary hyperparathyroidism*** - The patient's **PTH is significantly elevated** (over twice the upper limit of normal), which is a critical driver for **renal osteodystrophy** and vascular calcification in Stage 4 CKD. - Management is urgent to prevent irreversible bone loss and **cardiovascular complications**, often requiring dietary phosphate restriction, phosphate binders, or vitamin D analogues. *Renal anaemia* - While the hemoglobin of 95 g/L is low, it is common in **CKD Stage 4** and is not considered an acute emergency in an asymptomatic patient. - Management typically involves **erythropoietin-stimulating agents (ESAs)** once iron stores (ferritin and TSAT) are confirmed to be adequate. *Vitamin D deficiency* - A vitamin D level of 35 nmol/L indicates **insufficiency**, which contributes to the elevation of PTH but is not the primary clinical urgency itself. - It should be managed with **cholecalciferol or ergocalciferol** supplementation as part of the broader strategy to control secondary hyperparathyroidism. *Hypocalcaemia* - The calcium level of 2.05 mmol/L is only **mildly low** and the patient is asymptomatic, meaning it does not require immediate intravenous correction. - This mild hypocalcemia is a physiological trigger for the **PTH elevation** and is typically managed by correcting phosphate and vitamin D levels. *Hyperphosphataemia* - The phosphate level of 1.95 mmol/L is **elevated**, but it is not at a life-threatening level that would take precedence over the significantly high PTH. - Reducing phosphate through **dietary restriction** and phosphate binders is a key step, but it serves primarily as a means to control the **secondary hyperparathyroidism**.

Question 73: A 68-year-old man with type 2 diabetes presents to the emergency department with a 3-day history of vomiting and diarrhoea. His regular medications include metformin, ramipril, and furosemide. On examination, he appears dehydrated with reduced skin turgor. Blood pressure is 95/60 mmHg, pulse 105 bpm. Blood tests show: creatinine 385 μmol/L (baseline 95 μmol/L), urea 28.5 mmol/L, potassium 5.8 mmol/L. Urinalysis shows no protein or blood. What is the most appropriate initial management step?

A. Commence dopamine infusion
B. Intravenous 0.9% sodium chloride fluid resuscitation (Correct Answer)
C. Immediate haemodialysis
D. Intravenous furosemide 80 mg
E. Continue current medications and monitor closely

Explanation: ***Intravenous 0.9% sodium chloride fluid resuscitation*** - The patient presents with **pre-renal Acute Kidney Injury (AKI)** due to severe volume depletion from gastroenteritis, evidenced by **hypotension**, tachycardia, and a significant rise in creatinine and urea. - Restoring **renal perfusion** with intravenous crystalloids is the immediate priority to reverse the hypovolemia, improve kidney function, and prevent progression to acute tubular necrosis. *Commence dopamine infusion* - **Dopamine** is no longer recommended in the management of AKI, as studies have shown it does not provide renal protection or improve patient outcomes. - **Vasopressors** should only be considered if severe shock persists despite adequate fluid resuscitation, which is the initial and crucial step for hypovolemia. *Immediate haemodialysis* - While the patient has significant AKI and hyperkalemia (5.8 mmol/L), his **potassium** is not yet at a level typically requiring immediate emergency haemodialysis without attempting medical management. - **Haemodialysis** is reserved for specific emergent indications like refractory hyperkalemia, severe metabolic acidosis, or severe fluid overload with pulmonary edema, none of which are definitively present as an initial presentation without medical intervention. *Intravenous furosemide 80 mg* - Administering **loop diuretics** like furosemide to a patient who is already **hypovolemic** and hypotensive will worsen dehydration and further impair renal perfusion, exacerbating the AKI. - **Diuretics** are primarily indicated for managing fluid overload, not for improving kidney function in the setting of volume depletion. *Continue current medications and monitor closely* - Several of the patient's current medications, including **metformin**, **ramipril (an ACE inhibitor)**, and **furosemide**, are contraindicated or require temporary cessation in the context of AKI and dehydration. - **Metformin** carries a high risk of **lactic acidosis** with impaired renal function, while **ramipril** and **furosemide** can worsen renal function and hypovolemia, respectively; therefore, continuing them is inappropriate.

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