The Predictive Role of Thiol/Disulfide Homeostasis as an Oxidative Stress Parameter in Sarcopenic Obesity

<i>Background and Objectives:</i> Sarcopenic obesity (SO), characterized by the coexistence of excess adiposity and reduced muscle mass/function, is associated with adverse outcomes in older adults. Oxidative stress has been implicated in the pathogenesis of both obesity and sarcopenia. This study aimed to evaluate the association between thiol/disulfide homeostasis (TDH), ischemia-modified albumin (IMA), and SO in obese older adults. <i>Materials and Methods:</i> In this cross-sectional study, 132 obese individuals aged ≥65 years were enrolled from a geriatrics outpatient clinic. SO was defined based on the ESPEN/EASO criteria, incorporating anthropometric, body composition, and muscle function measures. Serum native and total thiol levels, disulfide concentrations, and IMA were assessed. Logistic regression identified independent predictors of SO, and ROC analysis evaluated the discriminatory power of oxidative parameters. <i>Results:</i> SO was present in 15.2% (<i>n</i> = 20) of participants. Patients with SO exhibited significantly lower native (<i>p</i> = 0.003) and total thiol levels (<i>p</i> < 0.001), and higher disulfide/native thiol (<i>p</i> = 0.009) and disulfide/total thiol ratios (<i>p</i> = 0.009). IMA levels were slightly elevated in SO but not significantly different (<i>p</i> = 0.13). In multivariable regression, age and disulfide/native thiol ratio were independent predictors of SO (OR = 5.71, <i>p</i> = 0.041). ROC analysis showed that disulfide/native thiol ratio had moderate predictive accuracy (AUC = 0.684, <i>p</i> = 0.008), with a cut-off > 6.63 yielding 92.86% specificity. <i>Conclusions:</i> Older adults with SO exhibit disrupted redox balance, as evidenced by altered TDH parameters. The disulfide/native thiol ratio may serve as a useful oxidative biomarker for identifying SO. These findings highlight the potential role of oxidative stress in SO and warrant further research into targeted antioxidant strategies.