Thiol/Disulfide Homeostasis as a New Oxidative Stress Marker in Patients with COPD

<b>Background and Objectives</b>: Chronic Obstructive Pulmonary Disease (COPD) is characterized by chronic inflammation and an imbalance between oxidative and antioxidative mechanisms. The aim of this study was to investigate oxidative balance and dynamic thiol/disulfide homeostasis in patients with COPD. <b>Materials and Methods</b>: A total of 68 participants, including 34 COPD patients and 34 healthy controls, were enrolled. Demographic characteristics, smoking status, comorbidities, inflammatory and biochemical parameters, and oxidative stress (OS) markers were recorded. Pulmonary function tests were performed, and COPD patients were classified according to GOLD stages. Correlation, ROC, and multivariate logistic regression analyses were conducted to evaluate the relationships between OS, disease severity, and potential confounders. <b>Results</b>: Among all participants, smoking and comorbidities were significantly more frequent in COPD patients compared to controls. COPD was associated with increased inflammatory and OS markers, characterized by reduced total and native thiol and total antioxidant status (TAS) levels, alongside elevated disulfide, total oxidant status (TOS), and oxidative stress index (OSI). ROC analysis showed strong diagnostic accuracy for thiol parameters, particularly total and native thiol. Thiol depletion and elevated OS were more pronounced with advancing GOLD stage. In multivariate analysis, smoking status was independently associated with COPD. <b>Conclusions</b>: Thiol/disulfide imbalance and OS are evident in COPD, suggesting potential clinical relevance for disease evaluation. However, larger studies are needed to confirm their role as reliable biomarkers or therapeutic targets.