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Spironolactone in renal impairment — GPhC CRA MCQ

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HardRenal and Hepatic ImpairmentSpironolactone in renal impairmentGPhC CRA

A patient with heart failure has taken spironolactone 25 mg daily for three months. They are clinically stable, but monitoring now shows potassium 5.7 mmol/L and eGFR 42 mL/min/1.73 m². What action best follows SPS guidance?

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Correct answer: B — Reduce the dose and arrange early repeat renal function and potassium

For heart-failure monitoring, SPS advises reducing the spironolactone dose when potassium is above 5.5 mmol/L; a common reduction is 25 mg on alternate days or halving the dose. Stopping and seeking specialist advice is the threshold response when potassium exceeds 6 mmol/L, so permanent withdrawal at 5.7 overstates the rule. Delayed review, potassium supplementation and substitution with another potassium-sparing diuretic are unsafe.

Reference: NHS SPS spironolactone monitoring: https://www.sps.nhs.uk/monitorings/spironolactone-monitoring/