A 72-year-old man presents with hyponatraemia (Na+ 118 mmol/L). He is confused but haemodynamically stable. Serum osmolality is low, urine osmolality ...

Question

A 72-year-old man presents with hyponatraemia (Na+ 118 mmol/L). He is confused but haemodynamically stable. Serum osmolality is low, urine osmolality is high and urine sodium is elevated. There is no evidence of hypovolaemia or oedema. What is the most likely underlying mechanism?

Accepted Answer

Syndrome of inappropriate antidiuretic hormone secretion (SIADH)

Answer

Hyperglycaemia causing pseudohyponatraemia

Answer

Hypovolaemic hyponatraemia due to gastrointestinal losses

Answer

Hypervolaemic hyponatraemia due to heart failure

Answer

Laboratory artefact

au-amc MCQ (SBA): Hyponatraemia - SIADH

A 72-year-old man presents with hyponatraemia (Na+ 118 mmol/L). He is confused but haemodynamically stable. Serum osmolality is low, urine osmolality is high and urine sodium is elevated. There is no evidence of hypovolaemia or oedema. What is the most likely underlying mechanism?