Night-time diuresis pattern in children with and without primary monosymptomatic nocturnal enuresis

Introduction Night-time polyuria as the dominating pathophysiological mechanism for primary monosymptomatic nocturnal enuresis (PMNE) has been put in question with nocturnal detrusor overactivity and high arousal thresholds as alternatives. An earlier finding of night-time polyuria in 12% of healthy non-enuretic schoolchildren underscores that excessive night-time diuresis per se is unlikely the major cause of PMNE. Objective The objective of this study was to compare the night-time diuresis pattern in children with and without PMNE and to evaluate the role of night-time polyuria in provoking enuretic episodes in children with PMNE. Study design Night-time diuresis pattern was recorded in 27 children with PMNE, aged 6–15 years, and 29 non-enuretic children, aged 6–13 years. Using a portable ultrasound recorder, the bladder volume was estimated at 15-min intervals for at least three nights with the child sleeping in its own bed at home. The volume of enuretic episodes was controlled using preweighed diapers. All voids were registered by time and volume. Diuresis during night time was estimated from the slope of regression lines fitted to ultrasound recording points. Mean night-time diuresis was calculated from total urine production during the night and time interval from the last void before bedtime to the first morning void. Results Night-time bladder filling pattern was recorded from 189 nights, giving 149 interpretable patterns for analysis (77 children with PMNE and 72 dry children). The night-time diuresis pattern was similar for children with or without PMNE, showing large variability between different nights of the same child. Most nights displayed a smooth bladder filling at constant low rate, whereas other nights showed an early phase with high diuresis followed by a longer period of low diuresis with no difference between the two groups. Discussion Night-time diuresis has been non-invasively monitored in children while asleep in their own beds at home. The
Funding Agencies|County of Ostergotland; Swedish Medical Research Council, Sweden; Ferring Lakemedel AB, Malmo, Sweden