Abstract
Diurnal decrease in serum sodium concentration related well to normalized diurnal weight gain (NDWG) among eight patients with chronic schizophrenia, polydipsia, and afternoon hyponatremia. This relationship is the cornerstone of the day-to-day clinical care of such patients. NDWG of 5% is associated with a decrease in serum sodium concentration of about 10 mmol/L. We tell how to develop individual guidelines for day-to-day management of patients subject to water intoxication.