Fatal water intoxication in a schizophrenic patient--an autopsy case.

We report a case of fatal water intoxication due to polydipsia. A 69-year-old schizophrenic male was found dead at his room of the hospital in which he had been admitted. Medico-legal autopsy was carried out to determine the cause of his death. The autopsy revealed no severe trauma leading him to the death. Internally, it was noticed that the stomach was vigorously expanded, including fluid contents. Intracardiac blood, being dark-red in color, seemed to be diluted. The both lungs ballooned aqueously, showing apparently edema. However, there was neither macroscopic nor histopathological lesion, being responsible for his death. Postmortem biochemical analyses revealed severe hyponatremia of 92 mEq/ml. In cases with short postmortem interval, serum sodium level almost similarly reflected antemortem level. According to his psychiatric doctor, he had been diagnosed as water intoxication due to polydipsia. Moreover, at 2 h before the discovery of his body, he had been found to drink much running water. It was concluded the cause of his death as fatal water intoxication.