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?
Q52
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?
Q53
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?
Q54
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?
Q55
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?
Q56
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?
Q57
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?
Q58
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?
Q59
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?
Q60
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?
Renal & Urology UK Medical PG Practice Questions and MCQs
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.
