Urinary N-acetyl-beta-glucosaminidase in normal Chinese children and children with pyelonephritis.

Urinary excretion of N-acetyl-beta-glucosaminidase (NAG) was measured in random urine as the ratio of NAG to grams of urinary creatinine in 120 normal Chinese children. The results showed that the NAG was elevated in newborn babies and infants, and decreased to adult level after two years of age. Thirteen children with urinary tract infection, who were clinically suggested or proved to have pyelonephritis, were evaluated for their urinary NAG excretion. The level of enzymuria at diagnosis in these patients was significantly higher than that of normal children for age. Eleven longitudinal follow-up data including levels at diagnosis, end of treatment, and two to four weeks after treatment showed that the mean urinary NAG at diagnosis was 109.82 +/- 87.30 u/g creatinine, compared with 75.26 +/- 48.82 u/g creatinine at the end of treatment and 15.37 +/- 9.69 u/g creatinine after recovery. These data suggest the presence of renal tubular cell injury in upper urinary tract infection. Thus urinary NAG may play a role in differentiating lower from upper urinary tract infections.