Nocturnal enuresis in children is associated with differences in autonomic control

Study Objectives To assess the relationship between urine osmolality, cardiovascular parameters, and nocturnal enuresis in a population of children undergoing polysomnographic assessment. Methods This prospective observational study included consecutive children aged 5-17 years presenting for overnight polysomnography. Children were evaluated using continuous ambulatory blood pressure monitoring to assess heart rate and blood pressure. Urine samples were collected throughout the night to determine urine sodium excretion and osmolality. Comparisons of results were made between children with and without a history of nocturnal enuresis. Results A total of 61 children were included for analysis; 13 had a history of nocturnal enuresis. Children with nocturnal enuresis had greater disruption in respiratory parameters including higher apnea-hypopnea index (mean difference 12.2 8.8 events/h, p < 0.05), attributable to more central respiratory events (mean difference 5.4 +/- 4.9, p < 0.05), and higher variability in both oxygen and carbon dioxide parameters compared to those without nocturnal enuresis. Sleep parameters, urine osmolality, and blood pressure did not differ between groups. Children with nocturnal enuresis showed an increase, rather than a decrease, in heart rate across the night (+5.4 +/- 19.1 vs. -6.0 +/- 14.8 beats/min, p < 0.05). Conclusions Children with a history of nocturnal enuresis have greater respiratory abnormalities, no differences in urine osmolality or blood pressure, and loss of normal heart rate decrease across the night. This pattern suggests that autonomic control, rather than renal or hemodynamic abnormalities, may contribute to the pathophysiology of nocturnal enuresis.