A 61-year-old man with small cell lung cancer has confusion and seizures. Sodium is 112 mmol/L, serum osmolality is low, urine osmolality is 620

Question

A 61-year-old man with small cell lung cancer has confusion and seizures. Sodium is 112 mmol/L, serum osmolality is low, urine osmolality is 620 mOsm/kg and urine sodium is 74 mmol/L. He is clinically euvolaemic. What is the most likely cause?

Accepted Answer

Syndrome of inappropriate antidiuretic hormone secretion

Answer

Nephrotic syndrome

Answer

Cerebral salt wasting

Answer

Hypovolaemic hyponatraemia

Answer

Primary polydipsia

SIADH — RACP Written MCQ

A 61-year-old man with small cell lung cancer has confusion and seizures. Sodium is 112 mmol/L, serum osmolality is low, urine osmolality is 620 mOsm/kg and urine sodium is 74 mmol/L. He is clinically euvolaemic. What is the most likely cause?