Regulation of arginine vasopressin in enuretic children under fluid restriction

Background. Treatment of primary nocturnal enuresis using 1-deamino-8-D-arginine-vasopressin is based on the hypothesis that antidiuretic hormone (arginine vasopressin [AVP]) secretion is insufficient during the night. Persisting doubts about the theoretical background of this treatment and first results pointing to a different AVP regulation in children with nocturnal enuresis were the motives for the present: study. Objective. To determine if children with primary nocturnal enuresis have different AVP levels during fluid restriction when compared with normal controls. Methods. Twenty-three children with nocturnal enuresis (median age, 11 years) were compared with a corresponding control group of 18 healthy children. Plasma osmolality, urine osmolality, and plasma AVP concentrations were determined before and after a defined fluid restriction. Results. Regarding plasma and urine osmolality, no differences were found between the two groups. AVP levels after fluid restriction, however, showed significant differences. To maintain osmolality, the plasma AVP concentrations of the controls rose to a median value of 5.7 pg/mL, (range: 0.9-29.0 pg/mL) in comparison to a median of 14.0 pg/mL (range: 3.5-64.0 pg/mL, P = .015) for the enuretic children. Conclusion. The results are consistent with the established fact that AVP secretion is a function of plasma osmolality. They contradict the hypothesis that enuretic children have a AVP deficiency that has to be supplemented. Rather, the results point to a defect at the AVP receptor level or of the signal transduction pathway.