ABSTRACT
Twenty children with primary nocturnal enuresis and 20 healthy children of the same age and sex were studied. Natural urination was used for the 24-h urine collection. It was found that urine osmolality and free water reabsorption during the night did not differ statistically significantly between the enuretic children and the healthy. The increased diuresis in the enuretic children was caused by a higher excretion of the osmotically active solutes, including sodium. Use of desmopressin reduced diuresis and natriuresis to normal levels. It is suggested that the main role in the pathogenesis of the studied form of nocturnal enuresis is played by a decrease in ion reabsorption, probably in the thick ascending Henle loop, which facilitates the increase in diuresis and occurrence of nocturnal enuresis.
