Question

A 68-year-old man with small-cell lung cancer develops hyponatraemia (Na 120 mmol/L) with low serum osmolality, high urine osmolality and euvolaemia on examination. What is the most likely cause of his hyponatraemia?

Accepted Answer

SIADH

Answer

Primary polydipsia

Answer

Hypovolaemic hyponatraemia due to vomiting

Answer

Hyperglycaemia

Answer

Pseudohyponatraemia due to hyperlipidaemia

Practice question

A 68-year-old man with small-cell lung cancer develops hyponatraemia (Na 120 mmol/L) with low serum osmolality, high urine osmolality and euvolaemia on examination. What is the most likely cause of his hyponatraemia?