The Role of Gamma-Glutamyl Transferase in Acute Exacerbation of Chronic Obstructive Pulmonary Disease Severity: A Cross-Sectional Study

Gamma-glutamyl transferase (GGT) is a liver enzyme that is involved in inflammation and oxidative stress. It has been hypothesized that elevated GGT may occur secondary to oxidative stress in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and can be used as an indicator of inflammation in these patients. The present study aimed to determine the relationship between serum GGT and arterial blood gas (ABGs) on the one hand and COPD severity in AECOPD patients on the other hand. Patients with AECOPD were evaluated for disease severity based on the global initiative for chronic obstructive lung disease (GOLD), Modified British Medical Research Council (mMRC), COPD Assessment Test (CAT), and spirometry assessment upon admission at the hospital. Moreover, the GGT level in patients was analyzed based on the severity of the disease. The data were analyzed using SPSS software (version 25.0) by proper statistical tests. The significance level was P˂0.05. The mean±SD of the CAT score in the patients was obtained at 19.6± 4.6. According to the mMRC scale, most patients were grade 2 (n=29, 52.7%) and grade 1 (n=17, 30.9%), respectively. In addition, according to GOLD criteria, most patients (n=34, 61.8%) had moderate and severe (n=16, 29.1%) disease, respectively. The median (IQR) GGT levels in patients with mMRC 0-1 were 28.7 (12.98) IU/L, and those with mMRC 2-4 were 21 (33) IU/L (P=0.770). Additionally, the median (IQR) of GGT levels in patients in GOLD A-B were obtained at 26(18) IU/L, and in patients in GOLD C-D were reported as 18 (23.80) IU/L (P=0.222). The results showed a significant positive relationship between GGT level and AECOPD severity (r=+0.277, P=0.04). Moreover, a significant negative relationship was observed between GGT level and forced vital capacity (FVC) (r=-0.268, P=0.04). According to the Pearson correlation test, There was no significant correlation between GGT level with arterial HCO3 (P=0.123), PCO2 (P=0.511), PO2 (P=0.888), FEV1 (P=0.356), and FEV1/FVC (P=0.975). In conclusion, while a significant positive relationship was found between GGT levels and AECOPD severity, the study suggests that serum GGT levels may not have clinical efficacy in differentiating between patients with varying intensities of AECOPD periods. Further research with larger sample sizes and consideration of additional factors is warranted to confirm these findings.