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Acute hyperkalaemia associated with AKI and potassium-retaining medicines — MSRA MCQ

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Hardall topics relevant for this examAcute hyperkalaemia associated with AKI and potassium-retaining medicinesMSRA

A 76-year-old man with HFrEF and CKD G3b is reviewed urgently after blood tests requested for reduced appetite and 3 days of diarrhoea. He takes ramipril 10 mg once daily, spironolactone 25 mg once daily, furosemide 40 mg once daily and bisoprolol. Three days ago, he started trimethoprim 200 mg twice daily for a culture-confirmed lower urinary tract infection. He is alert, has no palpitations, chest pain, weakness or dyspnoea, and is passing urine. Blood pressure is 112/68 mmHg and pulse is 74 beats/minute. His ECG shows sinus rhythm with no hyperkalaemia-related changes. The laboratory confirms that the sample was not haemolysed: potassium is 6.2 mmol/L, creatinine 142 micromol/L (baseline 104 micromol/L 6 weeks ago), and eGFR 34 mL/min/1.73 m² (baseline 49 mL/min/1.73 m²). What is the most appropriate management now?

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

Reveal the answer and explanation

Correct answer: B — Withhold trimethoprim, ramipril and spironolactone, and arrange immediate hospital assessment

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

This is clinically significant hyperkalaemia with acute kidney injury, rather than an isolated mildly raised potassium result suitable for community monitoring. Potassium is 6.2 mmol/L, the result is confirmed non-haemolysed, and creatinine has risen by more than 30% from baseline during an intercurrent dehydrating illness. Trimethoprim, ramipril and spironolactone all promote hyperkalaemia in this setting. A normal ECG does not make outpatient management appropriate: ECG changes correlate imperfectly with potassium concentration and can evolve unpredictably. He needs immediate hospital assessment for repeat potassium measurement, cardiac monitoring/serial ECG as indicated, assessment of AKI and treatment if potassium rises or ECG changes develop. The implicated medicines should be withheld pending review. B is attractive because he is asymptomatic with a normal ECG, but potassium at least 6.0 mmol/L plus AKI warrants urgent secondary-care referral rather than delayed surgery-based reassessment. C and D inadequately address the combined potassium-retaining drug burden and do not provide appropriate acute assessment. E would be reasonable only if pseudohyperkalaemia were genuinely suspected; here the sample is confirmed non-haemolysed and there are strong clinical precipitants.

Reference: Hyperkalaemia: Primary Care (Guidelines) (Crawled November 2025) — https://rightdecisions.scot.nhs.uk/tam-treatments-and-medicines-nhs-highland/adult-therapeutic-guidelines/fluid-and-electrolytes/hyperkalaemia-primary-care-guidelines/?searchTerm=care+right+decisions ACE inhibitors and angiotensin II receptor blockers monitoring (Last updated 12 August 2026) — https://sps.nhs.uk/monitorings/ace-inhibitors-and-angiotensin-ii-receptor-blockers-monitoring/ Spironolactone monitoring (Last updated 19 February 2026) — https://sps.nhs.uk/monitorings/spironolactone-monitoring/