TSI vs. TRAb in Graves’ disease: treatment monitoring, relapse prediction, and drug withdrawal decisions

Background Graves’ disease (GD) is the most common autoimmune cause of hyperthyroidism. This study compared thyroid-stimulating immunoglobulin (TSI) and thyrotropin receptor antibody (TRAb) for monitoring disease course, predicting relapse, and guiding antithyroid drug (ATD) withdrawal. Methods In a retrospective analysis of 330 GD patients at Guangzhou Red Cross Hospital (January 2023–March 2026), patients were stratified by TSI and TRAb level, treatment outcome (relapse, drug withdrawal, and continued treatment without remission) and disease duration, and antibody levels, thyroid function, and clinical data were analyzed. Results Regarding TSI/TRAb expression, TRAb − /TSI + patients had higher median TRAb levels than TRAb − /TSI − patients. The TRAb + /TSI + group demonstrated significantly higher FT3 levels and lower TSH levels compared to the TRAb + /TSI − group. With respect to treatment outcomes, TSI levels were significantly higher in the relapse group than in the drug-withdrawal group but not in TRAb levels. Higher TSI levels were associated with longer drug-withdrawal duration and disease duration in the relapse group. Across disease-duration groups, TSI and TRAb levels were highest in patients with disease duration < 4 months and were lower in the longer-duration groups. Conclusion TSI reflects response to ATD and disease activity, and demonstrated potential utility in guiding drug withdrawal timing and assessing relapse risk in this cohort. Across different disease-duration groups, TSI and TRAb exhibited broadly similar patterns in their levels and were associated with thyroid function parameters. These findings require validation in larger, prospective studies.