Objective: The aim of this study was to investigate the pathophysiologic cause(s) of primary nocturnal enuresis. Therefore, electrolyte concentrations of urine specimens were evaluated in the morning, and alterations compared between enuretics and nonenuretics.
Methods and patients: First morning urine specimens of 27 enuretics and 21 nonenuretic subjects fed the same diet were collected, and urinary electrolytes were measured. The urinary Ca/Cr ratio, tubular reabsorption of phosphorus (TRP) and fractional sodium (FE Na%) and potassium excretions (FE K%) were determined for patients and controls.
Results: There was no significant difference in the Ca/Cr ratio and TRP between patients and controls, but enuretic patients had significantly higher FE Na% and FE K% values than controls (p < 0.001). There were significant positive correlations between FE Na% and (r = 0.81, p < 0.001) FE K% and the frequency of bedwetting, respectively, among enuretic patients (r = 0.54, p < 0.001).
Conclusion: Since Na and K excretion of enuretic patients was higher than in nonenuretics, it can be concluded that there may be a benign hereditary and/or postural renal tubular handling disorder of Na and K in enuretic children.