Question

A 70-year-old man presents with serum sodium 118 mmol/L, low serum osmolality and inappropriately concentrated urine. He is euvolaemic on examination and taking an SSRI. TSH and cortisol are normal. What is the most likely diagnosis?

Accepted Answer

Syndrome of inappropriate antidiuretic hormone secretion (SIADH)

Answer

Hypovolaemic hyponatraemia due to diuretic use

Answer

Hypervolaemic hyponatraemia due to heart failure

Answer

Primary polydipsia

Answer

Pseudohyponatraemia due to hyperlipidaemia

Practice question

A 70-year-old man presents with serum sodium 118 mmol/L, low serum osmolality and inappropriately concentrated urine. He is euvolaemic on examination and taking an SSRI. TSH and cortisol are normal. What is the most likely diagnosis?