Hyponatremia due to antidepressant medications.

Presented is the case of an elderly woman who developed severe hyponatremia while taking tricyclic antidepressants. She met the criteria for the syndrome of inappropriate antidiuretic hormone secretion induced by drugs. Her symptoms of lethargy, weakness, and gastrointestinal disturbances developed insidiously, allowing the hyponatremia to reach severe levels before a diagnosis was made. A variety of psychoactive drugs, most prominently tricyclic antidepressants, have been reported to produce hyponatremia idiosyncratically in elderly persons.