Thiol–Disulfide Homeostasis and Erythrocyte Glutathione Balance in ST-Elevation Myocardial Infarction: A Prospective Case–Control Study

Background: ST-elevation myocardial infarction (STEMI) provokes intense oxidative stress. Serum thiol–disulfide and intracellular glutathione balances reflect oxidative status in different compartments and are rarely measured together. We compared both axes between patients with STEMI and chest-pain controls without chronic disease and examined their relation to infarct severity. Methods: In this prospective single-center case–control study, both axes were measured with automated assays in 90 patients with STEMI and 79 controls. Blood was drawn at first contact, before any drug and before reperfusion. Groups were compared with Welch t or Mann–Whitney U tests, with effect sizes, 95% CIs, and Benjamini–Hochberg correction. Results: All 10 markers differed between groups (adjusted p < 0.001). Patients had lower native thiol (315.0 (69.6) vs. 407.4 (63.3) µmol/L; Hedges’ g = −1.38) and higher disulfide (22.4 (6.8) vs. 16.9 (6.4) µmol/L; g = 0.82). Reduced glutathione was lower (733.2 (87.9) vs. 869.8 (83.7) µmol/L; g = −1.58) and oxidized glutathione higher, raising the GSSG/GSH ratio (median 0.074 vs. 0.030; r = 0.72). Differences persisted after adjustment for age and sex and within each sex. Within STEMI, marker–severity correlations were weak, and none survived correction. Conclusions: Both redox systems shift toward oxidation in STEMI. These markers were not graded indices of infarct severity, and no diagnostic or prognostic use is claimed.