Relationship between serum γ‑glutamyltransferase levels and acute exacerbation of chronic obstructive pulmonary disease

Abstract

γ-glutamyltransferase (GGT) is a plasma membrane enzyme, which is involved in antioxidant glutathione resynthesis. The aim of the study was to compare the serum levels of GGT (which is considered a novel marker of oxidative stress) between patients with stable chronic obstructive pulmonary disease (COPD) and those with acute exacerbation of COPD, and the relationship of GGT with inflammation. The study involved 132 patients with exacerbated COPD and normal function of the liver and biliary tract (mean age, 66.6 ±10.1 years; men, 88.6%) and 147 patients with stable COPD (mean age, 65.4 ±8.8 years; men, 87.1%). Serum GGT and C-reactive protein (CRP) levels were measured and compared between the groups. Serum GGT levels in patients with exacerbated COPD were significantly higher than in those with stable COPD (30 U/l; interquartile range [IQR], 18.8 vs. 25 U/l; IQR, 16; P <0.001]. Serum CRP levels were significantly higher in patients with exacerbated COPD compared with those with stable COPD (34 mg/l; IQR, 58.3 vs. 16 mg/l; IQR, 24.6; P <0.001). A significant positive correlation was observed between GGT activity and CRP levels (r = 0.27, P = 0.002). The GGT level of 29 U/l was set as a cutoff value of acute exacerbation with the specificity of 70.1% and sensitivity of 62.8% (95% confidence interval, 0.6-0.71; area under the curve, 0.66; standard error, 0.032; P <0.001). Our study indicates that serum GGT levels as the marker of oxidative stress increase during exacerbated COPD and correlate with CRP levels. The measurement of GGT activity may be useful in the evaluation of exacerbated COPD.