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Hypermagnesaemia from renal failure — SCE Acute Medicine MCQ

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ModerateAcute Renal and Metabolic EmergenciesHypermagnesaemia from renal failureSCE Acute Medicine

A 69-year-old woman is assessed on the acute medical unit. She has advanced CKD and has taken magnesium-containing laxatives. She is hypotensive, bradycardic and hyporeflexic. Initial assessment includes relevant observations, bedside tests and urgent blood results. What is the most likely diagnosis?

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Correct answer: B — Hypermagnesaemia

Hypermagnesaemia is the best answer because renal failure plus magnesium ingestion with bradycardia and hyporeflexia suggests hypermagnesaemia. Pulmonary embolism is plausible, but it is less appropriate for the physiology or timing described in this stem. The other distractors either fit a neighbouring presentation, delay definitive treatment, or miss the key immediate risk. Clinical pearl: Intravenous calcium can antagonise severe magnesium toxicity while elimination is addressed.

Reference: https://bnf.nice.org.uk/#acute-medicine-order-42-1