ECT as a possible treatment for SIADH: case report.

A 79-year-old man hospitalized for treatment of a major depressive episode was found to be hyponatremic, and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) was diagnosed. The SIADH had not been present on past medical evaluations and appeared to have developed during the course of the psychiatric illness. Other causes of SIADH were excluded. The SIADH showed very little response to the standard medical treatment of fluid restriction and intravenous normal saline. It improved dramatically during the course of 7 ECT sessions, paralleling the improvement in the patient's mood. It is suggested that ECT may be an effective treatment for SIADH, possibly exerting its effect on a specific hypothalamic dysfunction.