Intra-individual variability in voiding diaries of children with enuresis.

Background: Children with enuresis are often requested to complete voiding diaries in the diagnostic process. There is no consensus on the optimal number of days of registration in the voiding diary that would allow correct patient characterization.

Objectives: To examine the intra-individual variation in the parameters yielded from voiding diaries and evaluate if one week of registration is sufficient when evaluating the nocturnal urine production (NUP) and maximum voided volume (MVV) in children with monosymptomatic nocturnal enuresis (MNE).

Methods: We analyzed 228 voiding diaries completed for 14 days from treatment naïve children aged 6-14 years with MNE. NUP was estimated by diaper weight and volume of first morning void. MVV was registered both including and excluding first morning void.

Results: We found no significant differences in terms of NUP and MVV between week one and two, between one week or 14 days of registration, or when comparing two and four days of daytime registration. When using current ICCS definitions, 8 % of children with reduced MVV and no nocturnal polyuria and 12 % of children with nocturnal polyuria and normal MVV changed characterization when comparing two weeks of registration with two days of registration.

Conclusion: One week of nighttime-registration and two days of daytime-registration is sufficient to provide valid estimates of NUP and MVV. Two days could be sufficient to calculate subtype characterization according to ICCS definitions and possibly enhance compliance.