Purpose: This is a case report of a patient experiencing hyponatremia who was ultimately diagnosed with pituitary apoplexy-associated cerebral salt wasting syndrome (CSWS).

Methods: Laboratory tests, clinical evaluations, and magnetic resonance imaging were performed by specialists. Findings: The patient presented with severe headache, thirst, and polyuria. Results of laboratory tests indicated hyponatremia, decreased plasma osmolality, and elevated urine osmolality. Fluid restriction worsened the situation, and normal saline treatment helped return serum sodium and chloride levels to normal. Pituitary apoplexy-associated CSWS was finally considered. Implications: Pituitary apoplexy is a rare but reasonable etiology for CSWS with hyponatremia. Saline therapy is usually effective.