Question

A 40-year-old man presents with polyuria and polydipsia. Labs show serum sodium 150 mEq/L, plasma osmolality 310 mOsm/kg, and urine osmolality 90 mOsm/kg. After administration of desmopressin, his urine osmolality increases to 400 mOsm/kg. What is the most likely diagnosis?

Accepted Answer

Central diabetes insipidus

Answer

Primary polydipsia

Answer

Nephrogenic diabetes insipidus

Answer

SIADH

Answer

Osmotic diuresis from hyperglycemia

Practice question

A 40-year-old man presents with polyuria and polydipsia. Labs show serum sodium 150 mEq/L, plasma osmolality 310 mOsm/kg, and urine osmolality 90 mOsm/kg. After administration of desmopressin, his urine osmolality increases to 400 mOsm/kg. What is the most likely diagnosis?