Correlation between asymptomatic leukocyturia and urinary N-acetyl-β-d-glucosaminidase in women

Urinary N-acetyl-β-d-glucosaminidase (NAG) has been suggested as a marker for early diabetic nephropathy. This study aimed to prospectively investigate the relationship between asymptomatic leukocyturia (ASL) and NAG in women. One hundred and five female outpatients aged 31-86 years were selected for a 10-year follow-up study. We regarded ASL to be present if two consecutive samples were found to have 10 or more leukocytes/high-power field at 400× magnifications in a centrifuged midstream urine sample both at baseline and 10 years later. The urinary activities of NAG to creatinine ratios (NAG index) were measured in random spot urine samples. Patients without ASL at the beginning of the study were followed. The patients with ASL had diabetes mellitus more frequently than those without ASL at baseline and after 10 years. Residual urine volume and the NAG index were significantly higher in the former than in the latter (p = 0.014 and p = 0.002, respectively) at baseline. During the observation period, 15 patients had ASL (30.6%). Although a gradual increase in the NAG index was found during the study in both patients who had ASL and those who did not, the mean NAG index was significantly higher in the latter during study period (6.4 ± 3.0 vs. 9.8 ± 5.5, p = 0.004, 9.4 ± 5.2 vs. 11.5 ± 6.4, p = 0.328, respectively). On multiple logistic regression analysis, the NAG index at the beginning of the study was an independent predictor of ASL. These results demonstrate that the NAG index may serve as an indicator of ASL in women.