Urinary N-acetyl-β-D-glucosaminidase (NAG) activity in the early detection of diabetic nephropathy

One of the serious outcomes of diabetes mellitus is nephropathy. Measurement of microalbuminuria is a routine clinical practice for screening the diabetic nephropathy, but the injury to the kidney may be happening even without microalbuminuria. The association between urinary enzyme activities of N-acetyl-β-D-glucosaminidase (NAG) and angiotensin converting enzyme (ACE) and urine microalbumin was assessed in this study to define the possible biofactor for detection of early diabetic nephropathy. Urinary enzyme activities of NAG and ACE and urine microalbumin of 24 h, serum ACE, and some other clinical features are investigated in 35 type 2 diabetic patients. Glycated hemoglobin (HbA1c), triglycerides, serum ACE, and urine NAG were significantly elevated in diabetic groups compared to the healthy controls. There was no relation between urine NAG and microalbuminuria except in the group of diabetic patients which had urine NAG activity upper than 25 IU/ml; there was a correlation between urine NAG and serum ACE. We may conclude that before the finding of microalbumin in urine, the elevated urine NAG, as an early indicator of renal damage, is associated with serum ACE which is related to kidney vascular microangiopathies.