Serum Gamma Glutamyltransferase Is Associated with 25-Hydroxyvitamin D Status in Elderly Patients with Stable Coronary Artery Disease

Background: No previous study has investigated the association between gamma glutamyltransferase (GGT) and vitamin D in patients with stable coronary artery disease (CAD). We investigated the cross-sectional associations between vitamin D status as assessed by serum 25(OH)D and GGT. Methods: 169 patients were enrolled. Study population was divided into three groups: 1: 25(OH)D < 10 ng/mL (n = 59); 2: 25(OH)D 10–20 ng/mL (n = 82), and 3: 25(OH)D > 20 ng/mL (n = 28). Based on a cut-off GGT value identified in ROC analysis, we also divided the study population to compare the following groups: GGT ≤19 (n = 66) and GGT >19 (n = 103). Results: GGT activity was the highest in vitamin D severely deficient patients and the lowest in vitamin D insufficient patients. GGT was inversely correlated with 25(OH)D concentrations (R = −0.23; p = 0.002). The receiver operating characteristics curve identified the discrimination threshold of GGT of >19 U/L in predicting vitamin D deficiency. Higher leukocyte and neutrophil counts and lower 25(OH)D concentration were found in patients with GGT > 19 U/L. Conclusions: We identified an interaction between declining 25(OH)D levels and rising GGT levels with increasing age, which resulted in an unfavorable 25(OH)D-to-GGT ratio in stable CAD patients. These results suggest that these changes might further contribute to a high cardiovascular risk in the elderly.