Hyponatremia in patients with schizophrenia.

Although there is a definite association between hyponatremia and schizophrenia, the true incidence and etiology have not been established. This report is a retrospective study of all admissions to the Baroness Erlanger Hospital over a three and one-half year period. There was a 5.8% incidence of hyponatremia in patients with schizophrenia as compared with a 0.36% incidence for all admission (P less than .01). Schizophrenic patients at risk for developing hyponatremia drank water excessively(P less than .01) and were most likely to be taking thioxanthene (P = .05(4)) antipsychotic and anticholinergic medications (P Less than .01). Most schizophrenic patients admitted with hyponatremia had dangerously low serum sodium levels (less than or equal to 120 mEq) and showed severe neurologic dysfunction. This retrospective study compares the clinical features of schizophrenic patients who develop hyponatremia and those who do not. The possible role of antidiuretic hormone is discussed