Evaluating nocturnal polyuria in Japanese children with nocturnal enuresis.

Background The purpose of this study was to assess whether enuretic Japanese patients with nocturnal polyuria (NP) who met Hoashi's criterion (6-9 years: ≥200 mL; 10 years and older: ≥250 mL) met the International Children's Continence Society (ICCS; expected bladder capacity × 130%) and Rittig's criteria of nocturnal polyuria (>[age+9] × 20 mL). We also compared the effectiveness of 1-desamino-8-d-arginine vasopressin (DDAVP) among the three criteria. Methods Fifty-four patients who had NP with normal bladder capacity (36 boys [67%]; median age, 8 [interquartile range: 7-9]) were enrolled. We compared the diagnostic differences between the Hoashi and international standards (ICCS and Rittig's) for NP and the short-term effects of DDAVP. The patients received DDAVP for 8 weeks; we evaluated the association between each evaluation method and the effects of therapy. Results Only 17% of the patients met both Hoashi's and ICCS criteria, whereas 26% met both Hoashi's and Rittig's criteria. The therapeutic effect of DDAVP did not differ significantly between these two groups (effective rate of 73% [Hoashi's criterion] vs. 50% [ICCS criterion], P=0.19, and effective rate of 71% [Hoashi's criterion] vs. 62% [Rittig's criterion], P=0.84). Conclusions Hoashi's criterion is widely used, but according to both the ICCS and Rittig's criteria, approximately 80% patients did not fulfill the definition of NP. However, 8 weeks after the DDAVP treatment began, no significant difference was observed in the therapeutic effect of DDAVP according to each criteria. The definition of NP should account for the physical disparity between Japanese and Westerners.