THE INFLUENCE OF SMALL FUNCTIONAL BLADDER CAPACITY AND OTHER PREDICTORS ON THE RESPONSE TO DESMOPRESSIN IN THE MANAGEMENT OF MONOSYMPTOMATIC NOCTURNAL ENURESIS

Purpose: The relationship of functional bladder capacity as well as ot her variables to the responsiveness to desmopressin in children with m onosymptomatic nocturnal enuresis was investigated. Materials and Meth ods: A total of 95 children 8 to 14 years old with monosymptomatic noc turnal enuresis (6 or more of 14 nights wet) were evaluated in a doubl e-blind study followed by open label crossover extension using 20 to 4 0 mcg. desmopressin. Evaluated predictors of response included patient age, gender, race, family history, number of baseline wet nights, uri ne osmolality parameters and maximum functional bladder capacity (as a percent of predicted bladder capacity based on the formula, patient a ge + 2 x 30 = cc). Responders to desmopressin were classified as excel lent (2 or less of 14 nights wet) or good (50% or greater decrease but more than 2 of 14 nights wet) and nonresponders were defined by a les s than 50% decrease in wet nights. Results: Of the 95 patients 25 (29. 5%) achieved an excellent response to desmopressin and 18 (18.9%) had a good response for a cumulative response rate of 45.3%. The remaining 52 patients (54.7%) were nonresponders. There were no significant dif ferences between responders and nonresponders in regard to gender, rac e, positive family history or baseline urine osmolality parameters. Re sponse to desmopressin was associated with older age, fewer baseline w et nights and larger bladder capacity. Patients with a functional blad der capacity greater than 70% predicted bladder capacity were 2 times more likely to respond to desmopressin. Conclusions: The responsivenes s of children with nocturnal enuresis to desmopressin is adversely aff ected by reduced functional bladder capacity. The results of this stud y have implications regarding the potential use of combination pharmac otherapy with desmopressin and an anticholinergic for enuretic patient s who are nonresponsive to single drug therapy.