The role of bladder capacity in antidiuretic and anticholinergic treatment for nocturnal enuresis.

Abstract

We evaluated combination treatment with desmopressin and oxybutynin in patients with enuresis who did not respond to desmopressin monotherapy. Furthermore, we compared 2 methods of estimating bladder capacity and evaluated the ability of these methods to predict the response to desmopressin and oxybutynin. A total of 60 children with a mean age +/- SD of 10.6 +/- 3.0 years who had monosymptomatic nocturnal enuresis completed the study. After a 2-week observation period maximal voided volume during free access to fluid intake was determined by a 2-day frequency-volume chart and maximal voided volume after water load was determined on a separate day. Patients then received 20 mug desmopressin intranasally at bedtime during 2 weeks. In nonresponders to desmopressin with less than a 50% decrease in wet nights 5 mg oxybutynin twice daily was added for another 2 weeks. Of the patients 41 (68%) showed more than 50% decrease in wet nights during the 2-week desmopressin treatment period (4.6 +/- 1.6 to 0.7 +/- 0.8, p <0.001). In desmopressin nonresponders combined treatment with desmopressin and oxybutynin resulted in a further decrease in wet nights (4.0 +/- 1.2 to 1.7 +/- 1.4, p <0.001). Maximal voided volume during free access to fluid intake was significantly higher in desmopressin responders than in nonresponders (244 +/- 111 vs 160 +/- 65 ml, p <0.001). In contrast, maximal voided volume after water load was not significantly different between desmopressin responders and nonresponders. The study indicates a role for oxybutynin in combination with desmopressin in children who are not responding to desmopressin monotherapy. Maximal voided volume during free access to fluid intake is a clinically useful predictor of the response to desmopressin but not to oxybutynin.