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Severe drug-associated hyperkalaemia in CKD — MSRA MCQ

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HardNephrologySevere drug-associated hyperkalaemia in CKDMSRA

A 78-year-old man with type 2 diabetes and CKD G3b A3 is reviewed urgently after an abnormal blood result. His eGFR has been stable at 34–37 mL/min/1.73 m² for 8 months. He takes ramipril 10 mg once daily, dapagliflozin 10 mg once daily and finerenone 10 mg once daily. His potassium was 4.7 mmol/L and creatinine 154 micromol/L 3 weeks ago. Four days ago, he started trimethoprim for culture-confirmed lower UTI. He is now afebrile and reports improving urinary symptoms. He has no vomiting, diarrhoea, reduced oral intake, palpitations, weakness or chest pain. He has not used NSAIDs, potassium supplements or salt substitutes. The laboratory confirms that the sample was not haemolysed. Today, potassium is 6.6 mmol/L, creatinine is 232 micromol/L, eGFR is 21 mL/min/1.73 m² and bicarbonate is 19 mmol/L. What is the most appropriate immediate management action?

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

Reveal the answer and explanation

Correct answer: D — Withhold trimethoprim, ramipril and finerenone and arrange immediate emergency assessment with ECG monitoring

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

This is severe, likely drug-associated hyperkalaemia with acute deterioration in kidney function. Trimethoprim can raise potassium, particularly in people with renal insufficiency, diabetes and concurrent renin–angiotensin system inhibition; finerenone adds a further potassium-retaining effect. Its SmPC specifically advises that finerenone may need temporary discontinuation during trimethoprim treatment and requires withholding if potassium exceeds 5.5 mmol/L. ([medicines.org.uk](https://www.medicines.org.uk/emc/product/4566/smpc)) A confirmed potassium of 6.6 mmol/L requires urgent hospital assessment even if the patient is asymptomatic. UK primary-care guidance recommends urgent secondary-care referral for potassium at least 6.5 mmol/L and ECG assessment for potassium at least 6.0 mmol/L. ([rightdecisions.scot.nhs.uk](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&utm_source=openai)) Ramipril should also be stopped: NICE and SPS advise stopping ACE inhibitor/ARB treatment in CKD with potassium at least 6.0 mmol/L after stopping other potassium-raising medicines and seeking specialist advice. ([nice.org.uk](https://www.nice.org.uk/guidance/ng203/chapter/Recommendations?utm_source=openai)) A and D inappropriately delay emergency care. B recognises two contributors but underestimates the immediate arrhythmic risk and leaves ramipril in place. C may seem attractive because potassium binders have a role in selected hyperkalaemia, but outpatient potassium binding is not an adequate substitute for urgent monitored assessment in acute severe hyperkalaemia.

Reference: NICE NG203: Chronic kidney disease: assessment and management — Renin–angiotensin system antagonists for adults (2021; checked 16 August 2026) — https://www.nice.org.uk/guidance/ng203/chapter/Recommendations NHS Specialist Pharmacy Service: ACE inhibitors and angiotensin II receptor blockers monitoring (2021; checked 16 August 2026) — https://sps.nhs.uk/monitorings/ace-inhibitors-and-angiotensin-ii-receptor-blockers-monitoring/ Trimethoprim 50 mg/5 ml Suspension — Summary of Product Characteristics (2026; checked 16 August 2026) — https://www.medicines.org.uk/emc/product/4566/smpc