Erythrocyte Glutathione Shows a Larger Case–Control Difference than Serum Thiol-Disulfide Homeostasis at Emergency Department Presentation with Non-ST-Elevation Myocardial Infarction

Clinical redox studies usually sample a single compartment. In a single-centre, cross-sectional case–control study, we measured serum thiol-disulfide homeostasis, a bulk extracellular thiol measure, and erythrocyte glutathione, an intracellular measure, in the same blood draw from 82 patients presenting to an emergency department with non-ST-elevation myocardial infarction and 75 controls. Cases and controls differed substantially in sex and in cardiovascular risk profile. All nine redox indices differed between groups in the direction consistent with greater oxidation in patients. The standardized case–control difference was larger for erythrocyte reduced glutathione (Hedges g 1.14) than for serum native thiol (0.56). The post hoc bootstrap ratio of the two was 2.04 (95% confidence interval [CI] 1.31 to 4.08) before adjustment and 1.60 (0.99 to 3.23) after adjustment for age, sex and smoking, and no asymmetry was seen in the small subgroup free of recorded risk factors. In exploratory analyses within patients, serum indices were associated with the Synergy between Percutaneous Coronary Intervention with TAXUS and Cardiac Surgery (SYNTAX) score and reduced glutathione with ejection fraction. Each assay reports its own pool and is not a global measure of oxidative stress. In this sample, the compartment chosen determined the size of the observed case–control difference, a result that needs confirmation in a design with comparable groups.