[Water intoxication--a little known complication in the course of mental diseases].

Acute or chronic psychogenic polydipsia is a not uncommon finding in psychiatric patients. Water intoxication either results from the intake of large amounts of fluid within a short period of time and/or from a reduction of the renal "free water clearance". The latter can be caused iatrogenically by the administration of certain drugs or by the "Syndrome of Inadequate Secretion of ADH" (SIADH). Water intoxication results in cerebral oedema and may ultimately lead to death. A case is reported of iatrogenically-induced water intoxication in a patient with chronic psychogenic polydipsia.