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Hypokalaemic periodic paralysis — SCE Acute Medicine MCQ

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HardAcute Renal and Metabolic EmergenciesHypokalaemic periodic paralysisSCE Acute Medicine

A 29-year-old man of East Asian ancestry develops flaccid weakness after a carbohydrate-heavy meal. Potassium is 2.1 mmol/L, ECG shows U waves, sensation is intact and he has tremor and a small goitre. What is the best immediate diagnostic-treatment combination?

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Correct answer: E — Check thyroid status and replace potassium cautiously

The best answer is “Check thyroid status and replace potassium cautiously”. This is correct because the phenotype suggests thyrotoxic periodic paralysis. Potassium should be replaced carefully with ECG and biochemical monitoring because total-body depletion is limited and rebound hyperkalaemia can occur; the thyrotoxicosis also requires definitive treatment. Neuropathy, hypocalcaemia and cerebrospinal-fluid testing do not explain the meal-triggered hypokalaemic weakness.

Reference: UK Kidney Association potassium-emergency guidance: https://guidelines.ukkidney.org/hyperkalaemia/