skip to main content

Severe symptomatic SIADH-related hyponatraemia — SCE Acute Medicine MCQ

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

HardAcute Renal and Metabolic EmergenciesSevere symptomatic SIADH-related hyponatraemiaSCE Acute Medicine

A 50-year-old man with small-cell lung cancer has a generalised seizure. Sodium is 112 mmol/L, serum osmolality low, urine osmolality 680 mOsm/kg and he is euvolaemic. What is the most appropriate immediate management?

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

Reveal the answer and explanation

Correct answer: E — Give cautious hypertonic saline with close sodium monitoring

Seizures from severe symptomatic hypotonic hyponatraemia require cautious hypertonic saline to raise sodium enough to stop cerebral oedema. Fluid restriction alone is too slow for seizures. Rapid full correction risks osmotic demyelination. The likely mechanism is SIADH, but immediate management is driven by symptoms and sodium level.

Reference: European hyponatraemia guideline, Society for Endocrinology guidance