EXPRESS: Spexin as a Potential Biomarker for Autoimmune Inflammation in Graves' Disease.

Graves' disease (GD) is an autoimmune thyroid disorder characterized by excessive thyroid hormone production driven by thyroid-stimulating hormone receptor antibodies (TRAb). This study aimed to investigate the relationship between serum spexin (SPX) levels, TRAb levels, thyroid ultrasound findings, and metabolic parameters in GD patients, while evaluating SPX as a potential biomarker for autoimmune inflammation. A prospective, single-center study included 45 GD patients and 45 healthy controls. Serum TSH, fT3, fT4, anti-thyroglobulin, anti-thyroid peroxidase, TRAb, and SPX levels were measured. Thyroid ultrasonography classified patients into mild, moderate, and high heterogeneity groups. SPX levels were significantly higher in GD patients compared to controls (p < .001) and showed a strong positive correlation with TRAb levels (r = .579, p < .001) and thyroid heterogeneity (p < .001). Newly diagnosed patients (<6 months) exhibited the highest SPX levels, which decreased with prolonged disease duration. Receiver Operating Characteristic (ROC) analysis identified a cutoff value of 105 pg/mL for SPX, yielding 60% sensitivity and 91.1% specificity (AUC: 0.765, p < .001). SPX levels were also inversely correlated with disease duration and positively associated with inflammatory markers, suggesting its utility in monitoring disease activity and progression. These findings highlight SPX as a novel biomarker for assessing disease severity and autoimmune inflammation in GD. Incorporating SPX measurements into clinical practice may aid in early diagnosis, disease stratification, and therapeutic monitoring, ultimately improving personalized care for GD patients.