[Polydipsia and water intoxication in schizophrenia patients: report of two cases].

This report describes two cases of schizophrenia inpatients with polydipsia, intermittent hyponatremia, and water intoxication. Case 1, a 38 year-old male, developed polydipsia after seven years duration of schizophrenia, with a daily intake of water of more than 10 liters as a result of auditory hallucination suggestion. Nocturnal hyponatremia, agitation and exacerbation of psychosis were noted during admission. After 12 treatments of electroconvulsive therapy, the symptoms of psychosis and polydipsia declined. Case 2, a 42 year-old male, had also been a case of schizophrenia for about twenty years, and developed polydipsia with more than 5 liters of daily water intake in a chronic psychiatric hospital for a period of 5 years schizophrenia. He claimed that he enjoyed the pleasure of drinking water. The symptom of water intoxication had been noted intermittently in the past year, leading to at least two seizures. Finally the patient was transferred to our ward due to agitated mood, self-destructive behavior, consciousness loss, and motor weakness. The clinical features, differential diagnosis and treatment concept of polydipsia and water intoxication were also discussed in context.