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Nocturnal polyuria associated with dependent oedema and loop-diuretic timing — MSRA MCQ

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HardLUTSNocturnal polyuria associated with dependent oedema and loop-diuretic timingMSRA

A 78-year-old man with stable chronic heart failure presents with troublesome nocturia. He takes furosemide 40 mg each morning, ramipril and bisoprolol. He has bilateral ankle oedema by evening but no worsening exertional breathlessness, orthopnoea or paroxysmal nocturnal dyspnoea. He reports three large-volume nocturnal voids but no urgency, urge incontinence, hesitancy, weak stream or sensation of incomplete emptying. A 3-day frequency-volume chart shows a mean 24-hour urine volume of 1.8 L, of which 1.0 L is passed overnight. Urine dipstick is negative for blood, glucose, leucocytes and nitrites. Post-void residual volume is 40 mL, eGFR is 62 mL/min/1.73 m² and serum sodium is 139 mmol/L. He has reduced evening fluids and caffeine without benefit. What is the most appropriate next pharmacological management?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: B — Move furosemide 40 mg once daily to late afternoon

Explanation lettering: C = shown as A · E = shown as B · A = shown as C · B = shown as E

This is nocturnal polyuria: at age over 65 years, nocturnal urine production exceeding one-third of total 24-hour volume is abnormal; here it is 56%. The large nocturnal volumes, low residual volume and absence of urgency or voiding symptoms make overactive bladder and bladder outlet obstruction unlikely explanations. His dependent oedema and morning loop diuretic provide a plausible fluid-redistribution mechanism. NICE advises considering a late-afternoon loop diuretic for nocturnal polyuria. Moving his established furosemide dose to late afternoon shifts diuresis earlier in the evening while preserving necessary heart-failure diuresis. A is inappropriate because solifenacin treats bladder storage symptoms, not excess nocturnal urine production. B is inappropriate because there is no evidence of clinically significant voiding dysfunction or obstruction. C is initially attractive because desmopressin may be considered for nocturnal polyuria after other causes have been excluded, but this patient has heart failure requiring diuretic treatment. This is a contraindication to the licensed nocturia formulation because of fluid retention and hyponatraemia risk. D may reduce nocturnal urine output but risks fluid overload and heart-failure deterioration; the timing, rather than withdrawal, of diuresis should be adjusted.

Reference: NICE CG97: Lower urinary tract symptoms in men: management — Recommendations (2010; last reviewed December 2024) — https://www.nice.org.uk/guidance/cg97/chapter/recommendations Noqdirna 50 microgram oral lyophilisate — Summary of Product Characteristics (2026) — https://www.medicines.org.uk/emc/product/4372/smpc