Urinary excretion of n-acetyl-beta-D-glucosaminidase and retinol binding protein as alternative indicators of nephropathy in patients with type 1 diabetes mellitus.

Diabetic nephropathy (DN) is usually characterized by glomerular dysfunction, with microalbuminuria as an early indicator. Urinary excretion of smaller molecular weight proteins such as n-acetyl-beta-glucosaminidase (beta-NAG) and retinol binding protein (RBP) indicate proximal tubular dysfunction, and may identify diabetic patients at risk of developing diabetic nephropathy. In a trial to assess renal tubular function, urinary excretion of beta-NAG (by colorimetric assay) and RBP (by ELISA) were determined in 59 type 1 diabetic patients (mean age 15 +/- 3.