Urine output rate and maximum volume voided in school-age children with and without nocturnal enuresis.

OBJECTIVE: To compare urine volumes voided and output rates in prepubertal children with and without monosymptomatic nocturnal enuresis (MNE), to investigate the balance between nocturnal urine output and functional bladder capacity. STUDY DESIGN: In 76 prepubertal children with MNE, all voidings were collected over 48 hours: bedwetting volume (BWV), early-morning voiding after a dry night (EMV), and other voided volumes (VV). Output rates were calculated based on volumes voided and time intervals. Data collected in 50 typical prepubertal children were used for comparison. In both populations, holding-exercise volumes (HEV) were also collected, to approximate maximum volume voided (MVV). RESULTS: Of the 15% total bedwetting events recorded with output rates more than 2 standard deviations above the normal population average, only half met the International Children's Continence Society criteria for "nocturnal polyuria." The circadian rhythm of urine output is the same in both populations; during inactivity, low rates and long filling times result in large EMV. BWVs are also produced with low rates, but have shorter filling times. MVV is small for age in MNE, but HEV for age is the same in both populations. Treating MNE with holding exercises needs to be studied prospectively. CONCLUSIONS: The cause of bedwetting might be aborted bladder filling in the circadian inactivity phase rather than nocturnal polyuria.

Do holding exercises or antimuscarinics increase maximum voided volume in monosymptomatic nocturnal enuresis? A randomized controlled trial in children.

PURPOSE: We assessed prospectively the efficacy of holding exercises and/or antimuscarinics (oxybutynin chloride and placebo) for increasing maximum voided volume in prepubertal children with monosymptomatic nocturnal enuresis. MATERIALS AND METHODS: We randomly allocated 149 children to 5 groups, namely holding exercises with placebo (group A), holding exercises with oxybutynin (group B), placebo alone (group C), oxybutynin alone (group D) and alarm treatment (controls, group E). Maximum voided volume was the greatest voided volume from a 48-hour bladder diary, and holding exercise volume was the greatest volume produced with postponement of voiding after a fluid load, once daily for 4 days. Study medication, holding exercise procedures and alarm treatment were administered for 12 weeks. RESULTS: Holding exercises combined with placebo or oxybutynin significantly increased holding exercise volume and maximum voided volume, by 25% (p <0.001) and 21% (p <0.01), respectively, in group A, and by 43% (p <0.001) and 41% (p <0.001), respectively, in group B. Medication without holding exercises (groups C and D) did not increase holding exercise volume or maximum voided volume, and in these groups oxybutynin was not significantly superior to placebo. A borderline increase in holding exercise volume did not affect maximum voided volume in group E. Monosymptomatic nocturnal enuresis response was significantly lower with all 4 holding exercise volume modulating treatments (7%) compared to alarm therapy (73%). CONCLUSIONS: In the treatment of children with monosymptomatic nocturnal enuresis maximum voided volume can be increased significantly through holding exercises, but not with oxybutynin chloride alone. Compared to controls, increasing maximum voided volume had a minimal effect on monosymptomatic nocturnal enuresis.