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?
Q72
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?
Q73
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?
Renal & Urology UK Medical PG Practice Questions and MCQs
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.
