γ-glutamyltransferase as a predictor of chronic kidney disease in nonhypertensive and nondiabetic Korean men

Background: Little research has been done to examine whether γ-glutamyltransferase (GGT) is prospectively associated with the development of chronic kidney disease (CKD). We performed a prospective study to examine the association between GGT and the risk for the development of CKD. Methods: The study cohort included a total of 10 337 healthy males with normal baseline kidney functions and no proteinuria. Participants were workers in a semiconductor manufacturing company and its 13 affiliates. CKD was defined as either the presence of proteinuria or a glomerular filtration rate (GFR) of <60 mL · min^-1 · (1.73^2)-1. Cox proportional hazards models were used to calculate the adjusted hazard ratios in separate models for CKD. Results: During a follow-up period of 25 774.4 person-years, 366 men developed CKD. After adjustments were made for age, baseline GFR, triglyceride, and HDL-C, the risk for CKD increased with an increasing quartile of serum GGT (p for trend <0.001). The top one fourth of serum GGT vs the bottom one fourth of relative risks for CKD was 1.90 (95% confidence interval, 1.37-2.63). These associations were also apparent in participants who consumed ≤20 g/day of alcohol and those with normal weight, with values of alanine aminotransferase within reference intervals, or with C-reactive protein <3.0 mg/L, and participants without metabolic syndrome. Conclusions: Our findings, which were obtained from a large work-site cohort and excluded individuals with diabetes and hypertension, indicated that serum GGT may be an early predictor for the development of CKD, independent of baseline confounding factors.