Evaluation of nocturnal bladder capacity and nocturnal urine volume in nocturnal enuresis

To investigate the diagnostic accuracies of maximum voided volume (MVV) and first morning urine osmolality and compare these with accuracies of nocturnal bladder capacity (NBC) and nocturnal urine volume, respectively, in children with nocturnal enuresis.A total of 70 children with nocturnal enuresis were assessed (mean age 7.1 ± 2.2 years). Baseline parameters were obtained by measuring MVV using a voiding diary, first morning urine osmolality on a wetting day, diaper weight by checking twice per night and first morning urine volume.The proportions of small NBC and small MVV were 34.3% (24 cases) and 55.7% (39 cases), respectively. The proportions of low osmolality of first morning urine and nocturnal polyuria (NP) were 45.7% (32 cases) and 25.7% (18 cases), respectively. The sensitivity and specificity of small MVV for small NBC were 53.8% and 90.3%, respectively; the sensitivity and specificity of first morning urine osmolality for NP were 33.3% and 50.0%, respectively.The diagnostic accuracies of MVV and urine osmolality for small NBC and NP were only modest to low.