Diagnostic value of functional bladder capacity, urine osmolality, and daytime storage symptoms for severity of nocturnal enuresis

Purpose: To investigate the correlation between functional bladder capacity, first morning urine osmolality, daytime voiding symptoms, and severity of nocturnal enuresis.

Materials and methods: We assessed a total of 101 children with nocturnal enuresis (mean age, 7.7±2.3 years). Patients were divided into three groups according to the severity of enuresis: (1) one to six episodes per week (46 cases, 45.5%), (2) one episode every day (29 cases, 28.7%), and (3) multiple episodes every day (26 cases, 25.8%). Baseline parameters were obtained from frequency volume charts for 2 days, first morning urine osmolality, and a questionnaire for the presence of frequency, urgency, and daytime incontinence.

Results: The severity of enuresis increased with younger age (p=0.037) and reduced functional bladder capacity (p=0.007) and daytime symptoms of frequency and daytime incontinence (p=0.012, p=0.036). No statistical difference in urine osmolality or urgency was found among the three groups. Both reduced functional bladder capacity and low urine osmolality increased according to the severity of enuresis (p=0.012).

Conclusions: In children with nocturnal enuresis, severity was increased by younger age, reduced functional bladder capacity, and the presence of daytime voiding symptoms of frequency and daytime incontinence. The incidence of small functional bladder capacity was increased in children with everyday wetting, and the incidences of both small functional bladder capacity and low urine osmolality were increased in children with everyday multiple wetting.