Altered Thiol-Disulfide Homeostasis in Sarcoidosis: A Case-Control Study

Background and Objectives: Sarcoidosis is a multisystem inflammatory disorder associated with significant oxidative stress. This study aimed to evaluate dynamic thiol-disulfide homeostasis (TDH)-a systemic redox status indicator-in patients with sarcoidosis. Materials and Methods: This cross-sectional study enrolled 58 sarcoidosis patients (diagnosed via ATS/ERS/WASOG criteria) and 53 healthy controls. Concentrations of native thiol (NT) and total thiol (TT) were determined utilizing an automated spectrophotometric technique. Disulfide (DS) levels and proportional indices were calculated, and the association of TDH parameters with the presence of sarcoidosis (patients vs. healthy controls) was examined using receiver operating characteristic (ROC) and Cohen's d analysis. Results: Patients exhibited significantly reduced serum NT and TT levels compared to the control group (p = 0.003 and p = 0.009, respectively), whereas DS and the DS/NT ratio were elevated (p = 0.011 and p < 0.001). All parameters showed medium effect sizes. ROC analysis indicated that TDH parameters demonstrate an association with the presence of sarcoidosis, with AUC values ranging from 0.625 to 0.664. Among these, the DS/NT ratio showed the highest observed association with the disease group (AUC = 0.664), yielding 75.8% sensitivity and 60.3% specificity at a 5.7% cut-off. Conclusions: Our findings indicate that TDH is significantly altered in sarcoidosis, reflecting a systemic shift toward an oxidative state. These parameters appear to be exploratory biochemical indicators of systemic redox imbalance. To better understand their involvement in disease pathophysiology, future large-scale, prospective clinical trials might provide further insights.