Do electrolyte-containing beverages improve water imbalance in hyponatremic schizophrenics?

Background: To determine if ready access to a sodium-containing beverage ameliorates life-threatening water imbalance, we compared Gatorade to water in an ABA design. Method: Four male chronic schizophrenic inpatients with symptomatic hyponatremia drank water for 1 week. Gatorade plus water for 3 weeks, and then water again for 1 week. Afternoon plasma osmolality and morning serum sodium levels were used to estimate hydration status, and morning and afternoon urine creatinine concentrations were used to estimate fluid intake. Results: During the baseline phase, subjects were mildly polydipsic and mildly overhydrated in the morning and severely overhydrated in the afternoon. All subjects stated they preferred Gatorade and appeared to consume large quantities of it. Indices of fluid intake and hydration status did not differ between the two control phases, nor between the treatment phase and the other two phases. Frequency of severe hypo-osmolemia was also unaffected. Conclusion: Substitution of electrolyte-containing beverages is not likely to prevent water intoxication.