Assessment of urinary γ-glutamyltransferase and alkaline phosphatase for diagnosis of diabetic nephropathy.

Background: Urinary biomarkers of tubular damage can be useful for early diagnosis of diabetic nephropathy. Thus, the aim of this study was to test the diagnostic accuracy of the urinary excretion of γ-glutamyltransferase (GGT) and alkaline phosphatase (ALP) for diagnosis of diabetic nephropathy (DN).

Methods: Fasting glucose, fructosamine, serum creatinine, glomerular filtration rate (GFR), serum uric acid, serum albumin, and urinary albumin, creatinine, GGT and ALP were assessed in 74 type 2 diabetic patients without nephropathy and 38 type 2 diabetic patients with nephropathy.

Results: Urinary GGT and ALP were threefold higher in type 2 diabetic patients with nephropathy. Significant correlations were observed between urinary albumin and GGT (r=0.439, P<0.001) and urinary albumin and ALP (r=0.305, P<0.01). Areas under the curve for GGT and ALP were 0.7696 (P<0.001) and 0.7233 (P<0.001), respectively. At a cut-off value of 72U/g creatinine, GGT demonstrated a sensitivity of 96.0% and a specificity of 52.6%. At a cut-off value of 20U/g creatinine, ALP demonstrated a sensitivity and specificity of 83.8% and 36.8%, respectively.

Conclusions: Urinary GGT and ALP have potential value in the diagnosis of nephropathy in type 2 diabetic patients, but GGT has a slightly higher ability to discriminate nephropathy than ALP.