Urinary Levels of Renal Tubular Enzyme N-Acetyl-β-D-Glucosaminidase in Relation to Grade of Vesicoureteral Reflux

Elevated urinary levels of the renal tubular enzyme N-acetyl-beta-D-glucosaminidase (NAG) have been shown to be associated with tubular damage. To determine whether urinary levels of NAG would be abnormal and/or vary with the severity of vesicoureteral reflux, bladder urine was obtained from 31 children without reflux and 32 children with various grades of reflux. Nonrefluxing controls were obtained from children undergoing evaluation for a history of infection, hematuria or voiding abnormality. Patients with evidence of obstruction, neuropathic bladder dysfunction, urinary tract infection or renal failure were excluded. Bladder (32 cases) and ureteral (5 cases) urine from children with reflux was obtained at cystography or at antireflux surgery. Control and reflux patients were not significantly different with regard to sex or age. The mean urinary NAG level in nonrefluxing control patients was 10.63 IU/mg. (range 0.94 to 26.61, standard error of mean 0.43). Mean urinary NAG for all patients with reflux was 16.47 IU/mg. (range 2.85 to 52.02, standard error of mean 0.9). Two children with intrarenal reflux had urinary NAG levels of 52 and 48 IU/mg. Urinary NAG levels are elevated with higher grades of reflux and this relatively simple assay may have clinical usefulness in the assessment of tubular dysfunction associated with reflux.