Clinical predictors of TRAb decline after total thyroidectomy in patients with Graves' disease.

Objective: Thyrotropin receptor antibodies (TRAbs) are central to Graves' disease management, but their long-term kinetics after total thyroidectomy is poorly defined. We aimed to describe long-term TRAb trajectories and identify predictors of decline using clinically relevant thresholds. Methods: TRAb levels were measured serially in 1,516 patients after total thyroidectomy. Primary outcomes were time to TRAb < 10 and <2 IU/L, corresponding to a pragmatic fetal-risk threshold and assay negativity, respectively. Clinical factors (age, sex, body mass index, smoking, preoperative TRAb, and thyroid weight) were evaluated using Kaplan-Meier analyses and multivariable logistic regression. Results: TRAb levels declined rapidly, with median values falling below 10 IU/L within 2 years. Among patients with preoperative TRAb ≥ 10 IU/L, 84.8% reached <10 IU/L and 60.1% reached <2 IU/L within 5 years. In multivariable models, younger age, lower preoperative TRAb, and smaller thyroid weight independently predicted earlier decline, whereas sex, body mass index, and smoking did not. Conclusions: In this large post-operative cohort, younger age emerged as an independent predictor of accelerated TRAb decline after total thyroidectomy. Total thyroidectomy yields sustained TRAb decline and may promote immunological remission, particularly in younger patients, by removing the antigenic source before the establishment of long-lived plasma cells. These findings highlight age as a key determinant of TRAb kinetics and provide timelines for counselling and follow-up. Surgery may be especially valuable when a timely TRAb decline is required, such as in younger patients planning pregnancy or those with orbitopathy or antithyroid drug refractoriness.