Fatal water intoxication in a case of psychogenic polydipsia.

The term "water intoxication" is used to describe a condition of agitation, delirium, convulsion, and coma brought on by excessive intake of water, resulting in severe hyponatremia. Psychogenic polydipsia (compulsive water drinking) has until recently been considered a relatively benign process. Since 1974, however, three fatal cases of water intoxication, resulting from psychogenic polydipsia, have been reported. All three individuals died while hospitalized, thereby permitting performance of blood electrolyte determinations and documentation of the associated electrolyte imbalance. In the authors' case, there was a well-documented prior episode of water intoxication in which serum electrolytes showed a pattern typical of this entity. Death, however, occurred at home, thus preventing valid serum electrolyte determinations to be performed. Analysis of the vitreous humor revealed a severe hyponatremia, thus substantiating the diagnosis of fatal water intoxication. This case, once again, points out the usefulness of electrolyte analyses on the vitreous humor as an aid to establishing a cause of death.