Gamma-glutamyl transpeptidase as the marker of kidney graft function

Gamma-glutamyl transpeptidase (GGT) is a glycoprotein of the external surface of various cell types. The activity of GGT has been observed in cells and tissues with secretory activity, such as the proximal tubular cells in kidneys. GGT also plays an important pro-oxidant role, stimulating the generation of hydroxyl radicals, and increases membrane lipid peroxidation.

In this study we examined whether the monitoring of GGT activity in urine may be a prognostic factor of kidney allograft function. The study enrolled 107 Caucasian renal transplant recipients.

Urine samples were collected for GGT and creatinine analysis on the 1st day after transplantation, and then in the 3rd and 12th month.

Higher urine GGT activity in the 3rd month after transplantation was associated with significantly higher risk of graft failure (HR=1.063 per each U/g creatinine; 95%Cl:1.004-1.127; p=0.037) in the Cox proportional hazards model. Moreover, there were positive correlations between urine GGT and the grade of interstitial fibrosis (Rs=0.64, p=0.01) and tubular atrophy (Rs=0.54, p=0.056) in specimens collected in the 3rd month after transplantation.

Our results suggest that higher urine GGT activity in the 3rd month after transplantation may be a prognostic factor of graft failure.