Clinical outcomes of thyroid function in patients with thyrotropin receptor blocking antibody-positive hypothyroidism

Abstract Context Thyrotropin receptor blocking antibodies (TBAbs) are uncommon but not a rare cause of hypothyroidism. However, clinical outcomes of thyroid function in patients with TBAb-positive hypothyroidism remain unclear. Objective The aim of this study was to explore the clinical outcomes of thyroid function in patients with TBAb-positive hypothyroidism and investigate factors associated with hypothyroidism outcomes. Methods A single-center retrospective observational study was conducted from 2024 to 2025. Overall, 137 patients with TBAb-positive hypothyroidism without Graves’ disease (Non-GD group) and 181 with TBAb-positive hypothyroidism during or after antithyroid drug therapy for Graves’ disease (Prior GD group), almost all Japanese, were included. Thyroid functional outcomes were assessed in all patients; serial TBAb measurements were available for 31% and 36% of the patients, respectively. The main outcome was thyroid function at the final visit after a median follow-up period of 6.8 years. Clinical factors associated with hypothyroidism outcomes were analyzed using logistic regression analysis. Results Hypothyroidism persisted in 84% and 43% of the patients in the Non-GD and Prior GD groups, respectively. In both groups, persistent TBAb positivity was associated with hypothyroid outcomes (Non-GD: univariate analysis, odds ratio [OR], 3.51; 95% CI, 1.14-40.6; P = .013; Prior GD: univariate analysis, OR, 6.75; 95% CI, 1.87-24.4; P = .0016; multivariate analysis, OR, 6.88; 95% CI, 1.89-25.1; P = .0015). Conclusion Most patients with TBAb-positive hypothyroidism remain hypothyroid over the long term, whereas outcomes are more heterogeneous in patients with prior Graves’ disease who develop TBAb-positive hypothyroidism. Persistent TBAb positivity is associated with the hypothyroidism outcomes.