Polydipsia, Hyponatremia, and Water Intoxication Among Psychiatric Patients

Abstract

Many psychiatric patients suffer from excessive water intake, leading to hyponatremia-lower than norma! concentrations of plasma sodium-and water intoxication, a neurologic syndrome characterized by headaches, ataxia, lethargy, confusion, slurred speech, tremors, restlessness, urinary incontinence, and, in more serious cases, by focal and generalized seizures, stupor, coma, and death. Some of the diagnostic terms applied to these disorders of water intake are compulsive polydipsia, primary polydipsia, and self-induced water intoxication. An accurate diagnosis requires careful psychiatric and neuroendocrine evaluation (1). Reported rates of polydipsia among hospitalized psychiatric patients range between 6 and 17.5 percent, differing by type of institution and case-finding method (2-4). About half of these patients develop water intoxication. A mortality rate as high as 18.5 percent due to complications of water intoxication has been reported (5). About 80 percent of psychiatric patients with polydipsia and water intoxication have a diagnosis of schizophrenia. Other diagnoses asso-