Hypopituitarism and hyponatremia in a case with nasopharyngeal carcinoma.

We report a case of nasopharyngeal carcinoma (NPC) accompanied by hyponatremia and polyuria which was induced by tumor invasion into the pituitary gland. Magnetic resonance imaging showed the pituitary gland pushed upward by NPC. Hypopituitarism due to an intracranial tumor and the extracellular volume excess due to chemotherapy caused hyponatremia and polyuria. As the intracranial tumor was diminished by chemotherapy and irradiation, pituitary hormones were normalized. In patients with T4 NPC, pituitary-adrenocortical function should be endocrinologically evaluated before treatment.