skip to main content

Medication-related hyponatraemia and falls — SCE Acute Medicine MCQ

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

HardMedicine in the ElderlyMedication-related hyponatraemia and fallsSCE Acute Medicine

An 80-year-old woman presents after two falls and new confusion. Sodium is 119 mmol/L with serum osmolality 258 mOsm/kg and urine osmolality 510 mOsm/kg. She started sertraline three weeks ago and is euvolaemic on examination. There are no seizures. What is the most likely underlying cause?

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

Reveal the answer and explanation

Correct answer: A — SSRI-associated syndrome of inappropriate antidiuresis

Euvolaemic hypotonic hyponatraemia with inappropriately concentrated urine after starting an SSRI is consistent with SIAD. Diabetes insipidus causes dilute urine and hypernatraemia rather than hyponatraemia. Primary polydipsia usually has maximally dilute urine. The pearl is that new SSRIs are a common reversible cause of falls and delirium through hyponatraemia.

Reference: Society for Endocrinology hyponatraemia guidance; BNF