Question

A 45-year-old woman with small cell lung cancer develops hyponatraemia (Na 120 mmol/L), low serum osmolality and inappropriately concentrated urine. She is euvolaemic. What is the most likely diagnosis?

Accepted Answer

Syndrome of inappropriate antidiuretic hormone secretion

Answer

Primary polydipsia

Answer

Hypovolaemic hyponatraemia from vomiting

Answer

Pseudohyponatraemia due to hyperlipidaemia

Answer

Hyperglycaemia-induced hyponatraemia

Practice question

A 45-year-old woman with small cell lung cancer develops hyponatraemia (Na 120 mmol/L), low serum osmolality and inappropriately concentrated urine. She is euvolaemic. What is the most likely diagnosis?