skip to main content

Severe hyperkalaemia with persistent ECG changes in a haemodialysis patient — MRCEM SBA MCQ

Instant feedback + full explanation. One question, done properly.

HardResuscitation and critical illnessSevere hyperkalaemia with persistent ECG changes in a haemodialysis patientMRCEM SBA

A 64-year-old man who is anuric and receives maintenance haemodialysis presents after missing a session. Laboratory potassium is 7.2 mmol/L; a venous blood gas gives a similar result. His ECG shows absent P waves and a QRS duration of 156 ms, compared with 90 ms on a previous ECG. He is conscious, with a pulse of 52/min and blood pressure of 108/64 mmHg. Continuous cardiac monitoring is in place. He receives 30 mL of 10% calcium gluconate intravenously over 10 minutes and, concurrently, 10 units of soluble insulin with 25 g of intravenous glucose. Eight minutes after the calcium dose finishes, the insulin–glucose infusion has also finished, but the QRS remains 156 ms. His blood glucose before insulin was 5.6 mmol/L, and no subsequent glucose infusion has been started. Which management plan is most appropriate now?

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

Reveal the answer and explanation

Correct answer: B — Repeat 30 mL of 10% calcium gluconate, start a 10% glucose infusion, and arrange urgent haemodialysis.

Persistent QRS widening eight minutes after a full calcium gluconate dose indicates that myocardial stabilisation has not been achieved. Repeat the full 30 mL dose of 10% calcium gluconate while continuing ECG monitoring; calcium protects the heart but does not remove potassium. His pretreatment glucose was below 7 mmol/L, so the completed insulin–glucose treatment should be followed by 10% glucose at 50 mL/hour for five hours, with serial glucose checks. Because he is anuric and has missed dialysis, arrange urgent renal assessment and haemodialysis rather than relying on temporary intracellular potassium redistribution. ([doclibrary-rcht.cornwall.nhs.uk](https://doclibrary-rcht.cornwall.nhs.uk/GET/d10173287)) A provides appropriate immediate calcium and glucose but delays planning definitive potassium removal. C omits calcium despite persistent ECG toxicity; repeating insulin immediately also increases hypoglycaemia risk before its initial effect can be fully assessed. D gives one-third of the recommended calcium gluconate dose: 10 mL of *calcium chloride* 10%, not calcium gluconate 10%, supplies the equivalent calcium dose. E proposes a potassium binder that may be used alongside emergency treatment but cannot replace prompt myocardial stabilisation. ([gov.uk](https://www.gov.uk/drug-safety-update/calcium-chloride-calcium-gluconate-potential-risk-of-underdosing-with-calcium-gluconate-in-severe-hyperkalaemia))

Reference: Adult Hyperkalaemia Management Clinical Guideline, version 7.0 (December 2025) — https://doclibrary-rcht.cornwall.nhs.uk/GET/d10173287 Calcium chloride, calcium gluconate: potential risk of underdosing with calcium gluconate in severe hyperkalaemia (27 June 2023) — https://www.gov.uk/drug-safety-update/calcium-chloride-calcium-gluconate-potential-risk-of-underdosing-with-calcium-gluconate-in-severe-hyperkalaemia A Clinical Guideline for the Management of Hyperkalaemia in Adults (Approved August 2024) — https://www.nnuh.nhs.uk/publication/download/hyperkalaemia-in-adults-jcg0020-v6