The effect of alarm treatment on the functional bladder capacity in children with monosymptomatic nocturnal enuresis.

Purpose: We studied the characteristics of a group of monosymptomatic nocturnal enuretics successfully treated with the alarm system, with special reference to changes in functional bladder capacity.

Materials And Methods: The diaries of 7 girls and 19 boys 7 to 13 years old with severe nocturnal enuresis, small daytime bladder capacity (70% or less of expected capacity for age) and poor or absent response to desmopressin were analyzed. Patients were treated with an alarm until complete dryness was achieved for 21 consecutive nights before ending therapy. Immediately after the treatment they recorded a 1-week followup diary of voiding and fluid intake.

Results: Mean duration of the alarm treatment was 82 days, and there was no change in nocturnal or 24-hour diuresis from baseline to followup. Nocturia developed during the alarm treatment in 48% of the children. The nocturnal diuresis on nocturia nights was significantly higher than on nights without nocturia. Daytime functional bladder capacity increased significantly in children with and without nocturia.

Conclusions: Treatment with an alarm system increases daytime functional bladder capacity significantly in children with and without nocturia. A higher nocturnal urine production on nocturia nights explains why some children have nocturia and others do not.