Role of urine osmolality as a predictor of the effectiveness of combined imipramine and desmopressin in the treatment of monosymptomatic nocturnal enuresis

Background: We examined the usefulness of urine osmolality, as a predictive factor in the treatment of monosymptomatic nocturnal enuresis (NE) with combination therapy of imipramine and desmopressin. Methods: From May 2014 to April 2015, 59 monosymptomatic NE patients participated in this study. Early morning urine osmolality was measured at 1 week and 1 day before combination therapy of imipramine and desmopressin, and at 1 week and 2 weeks after therapy. The response to combination therapy was evaluated at 3 months after treatment. The mean period of combination therapy was $6.4{\pm}4.2weeks$. Therapeutic response was classified as complete (0-1 wet night/week), partial (over 50% reduction of night) and non-responders (less than 50% reduction of night). Results: The cumulative rate of the complete and partial responders was 76.3%. Among the 3 groups, the statistically lowest value of pre-treatment urine osmolality was observed in the complete responder group (p<0.001). Urine osmolality increased in all groups after treatment, however, statistically the greatest difference between pre and post-treatment urine osmolality was observed in the complete responder group (p=0.024). No serious side effects were observed. Conclusion: Early morning urine osmolality and change of urine osmolality between pre and post-treatment have predictive values in the response to combined imipramine and desmopressin for treatment of monosymptomatic NE.