The role of urine osmolality and ions in the pathogenesis of primary enuresis nocturna and in the prediction of responses to desmopressin and conditioning therapies.

Aim of the study was to determine the role of nocturnal and daytime urine volume, osmolality and ion excretions in the pathogenesis of primary monosymptomatic enuresis nocturna (PMEN) and in the prediction of response to desmopressin and conditioning therapies. Fifty-five children with PMEN between the ages 5 and 15 years were included to the study. The patients were randomly divided into three groups Group 1: Twenty enuretics having intranasal desmopressin 1x 20 microg treatment for 2 months Group 2: Twenty enuretics having conditioning therapy for 2 months. Group 3: Fifteen enuretics having intranasal izotonic solutions as placebo. The control group consisted of 15 healthy children. Urine osmolality, sodium, potassium, chloride, magnesium and creatinine levels were investigated in both daytime and nighttime urines. Fractional sodium, potassium, magnesium, chloride excretions were calculated. Wilcoxon, Mann-Whitney U, Kruskal-Wallis, Chi-square, Student's t and Pearson correlation tests were performed. The ratio of night/daytime urine osmolality was significantly decreased in enuretic children. In addition, the ratio of night/daytime urine Cl and K excretions were also significantly decreased in enuretics. Response rate to desmopressin and conditioning treatments were statistically higher than placebo control. The difference between response rates of desmopressin and conditioning therapies was not found statistically significant. Pretreatment values of urine volume osmolality and ions were not observed as predictive factors in response to desmopressin or conditioning therapy. In conclusion, nightly decreased potassium and chloride excretions were found to have a role in the pathogenesis of primary enuresis nocturna. Urine volume, osmolality and ion excretions are not suggested to be used in the prediction of response to desmopressin and conditioning therapies.