Serum Gamma-Glutamyl Transferase Activity as a Potential Novel Cardiovascular Biomarker in COPD.

Background: Gamma-glutamyl transferase (gamma-GT) is an enzyme present in the cell membranes, which is used as a new biomarker in prediction of inflammation, myocardial infarction, stroke, and cardiac death. The objective of this study was to investigate the relationship between serum levels of gamma-GT and cardiovascular disease in subjects with COPD and the correlation between serum gamma-GT level and degree of the limitation of air flow in COPD.

Methods: A total of 70 subjects (46.1%) with Global Initiative for Chronic Obstructive Lung Disease (GOLD) A-B and normal function of the liver and biliary tract (mean age [IQR] 59 [51.75-70] y; 77.1% men) and 82 subjects (53.9%) with GOLD C-D (mean age [IQR] 59 [56-66] y; 79.3% men) participated. Serum levels of gamma-GT and C-reactive protein were measured and compared between the 2 groups.

Results: The serum level of gamma-GT was found to be significantly (P < .001) higher in the GOLD stage C and D group than in the GOLD stage A and B group. Mean values of C-reactive protein, aspartate aminotransferase, and alanine aminotransferase did not differ significantly between the 2 groups. The prevalence of cardiovascular disease was statistically significantly higher in subjects in the GOLD stage C and D group than in the GOLD stage A and B group (P < .001). The serum level of gamma-GT was higher in subjects with COPD with coexisting cardiovascular disease than in those without cardiovascular disease (64 units/L [interquartile range 57-72.5] vs 17.5 units/L [interquartile range 10-25]).

Conclusions: Our results demonstrate that serum levels of gamma-GT may be helpful in grading the severity of COPD as the marker of oxidative stress, and there is a strong correlation between high serum levels of gamma-GT and cardiovascular events in subjects with COPD.