Increased urine volume in chronic schizophrenic patients.

Polydipsia and polyuria have a long association with schizophrenia. To assess the prevalence of polydipsia and polyuria in schizophrenia, urine volume was examined in medication-free chronic schizophrenic patients, normal controls, and nonschizophrenic patients. Mean urine volume was significantly higher in the schizophrenic patients (2319 +/- SD 2052 ml/24 hours) than in the other two groups (1054 +/- SD 471 ml/24 hours for nonschizophrenic patients and 1265 +/- SD 613 ml/24 hours for normals). Seven of 35 patients with schizophrenia but 0/7 nonschizophrenics had urine volumes greater than any normal control. Polyuria was associated with a good premorbid history and a positive neuroleptic response. Among polyuric patients, those with hyponatremia may represent a different, distinct subgroup. Neuroleptic treatment was associated with a further, significant increase in urine volume. Hence, polydipsia and polyuria appear to be relatively common in schizophrenia.