Measurement of N-acetyl-beta-glucosaminidase and its isoenzymes in urine methods and clinical applications.

1. N-Acetyl-beta-glucosaminidase is the most widely used urinary enzyme assay for the assessment of renal disease and the detection of nephrotoxicity. 2. An increase in N-acetyl-beta-glucosaminidase activity in urine is a sensitive test for renal tubular damage, since its relative molecular mass (M(r) > 130,000) precludes its filtration by the glomerulus and it is the most active of the glycosidases found in the lysosomes in the proximal tubule. 3. The analytical methods available for the determination of urinary N-acetyl-beta-glucosaminidase include fluorometric, colorimetric, spectrophotometric and a dipstick test. 4. The isoenzyme profile of N-acetyl-beta-glucosaminidase in urine varies at different stages of renal disease and damage. In particular there are increases in the B and I2 forms which may reflect perturbation of the cellular biosynthetic processes. 5. The value of N-acetyl-beta-glucosaminidase assays in various areas of medicine is briefly discussed and attention paid to its future role.