URINARY LEVELS OF THE RENAL TUBULAR ENZYME N-ACETYL-BETA-D-GLUCOSAMINIDASE IN UNILATERAL OBSTRUCTIVE UROPATHY

Elevated urinary levels of the renal tubular enzyme, N-acetyl-beta-D-g lucosaminidase (NAG), have been shown to be associated with reversible tubular damage and, therefore, may serve as an indicator of tubular d amage in the setting of presumed obstruction uropathy. This study comp ares urinary NAG levels in children with apparent upper tract obstruct ion with normal children to assess the sensitivity of this assay for t he detection of possible renal tubular damage. The study included 40 c hildren 3 weeks to 16 years old with unilateral ureteropelvic junction obstruction (30) or primary obstructive megaureter (10). Urine was ob tained from the bladder in all children and from the renal pelvis or u reter in 30 patients at surgery. Pelvic and ureteral urinary NAG level s were consistently higher than bladder levels. In patients with urete ropelvic junction obstruction NAG levels were 7 times higher than norm al (76 units per mg., p <0.0001) and 3 times higher than normal in pat ients with obstructive megaureter (29 units per mg., p <0.001). The me an bladder urinary NAG levels in patients with ureteropelvic junction obstruction (17.6 units per mg. creatinine, standard error of mean 2.0 1, p <0.001) and megaureters (19.2 units per mg. creatinine, standard error of mean 3.6, p <0.049) were elevated above control patients (10. 6 units per mg. creatinine, standard error of mean 1.02). Elevated uri nary NAG levels in the renal pelvis, ureter and bladder may be helpful in identifying upper tract obstruction, which if left untreated, migh t cause progressive renal deterioration.