Long-term Effect of Thyrotropin-binding Inhibitor Immunoglobulin on Atrial Fibrillation in Euthyroid Patients.

OBJECTIVE: Individuals with hyperthyroidism are at an increased risk of atrial fibrillation (AF), but the association between autoantibodies and AF or cardiovascular mortality in individuals who have returned to normal thyroid function remains unclear. METHODS: The study utilized electronic medical records from National Taiwan University Hospital between 2000 and 2022. Each hyperthyroidism patient had at least 1 thyrotropin-binding inhibiting immunoglobulin (TBII) measurement. The relationship between TBII levels and the risk of AF and cardiovascular mortality was assessed using multivariable Cox regression models and Kaplan-Meier survival analysis. RESULTS: Among the 14 618 enrolled patients over a 20-year timeframe, 173 individuals developed AF, while 46 experienced cardiovascular mortality. TBII values exceeding 35% were significantly associated with an elevated risk of AF for both the first TBII (hazard ratio {HR} 1.48 [1.05-2.08], P = .027) and mean TBII (HR 1.91 [1.37-2.65], P < .001). Furthermore, after free T4 levels had normalized, a borderline association between first TBII and AF (HR 1.59 [0.99-2.56], P = .056) was observed, while higher mean TBII increased AF (HR 1.78 [1.11-2.85], P = .017). Higher first and mean TBII burden continued to significantly impact the incidence of cardiovascular mortality (HR 6.73 [1.42-31.82], P = .016; 7.87 [1.66-37.20], P = .009). Kaplan-Meier analysis demonstrated that elevated TBII levels increased the risk of AF and cardiac mortality (log-rank P = .035 and .027, respectively). CONCLUSION: In euthyroid individuals following antithyroid treatment, elevated circulating TBII levels and burden are associated with an elevated risk of long-term incident AF and cardiovascular mortality. Further reduction of TBII level below 35% will benefit to clinical outcomes.

Clinical Characteristics of Graves' Disease Patients with Undetectable Thyrotropin Binding Inhibitor Immunoglubulin (TB2) / 대한내분비학회지

Background: Graves disease is an autoimmune disease caused by TSH receptor antibodies. Thyrotropin binding inhibitor immunoglobulins(TBII) are detected in most Graves patients, but some patients have no TBII activities in their sera. It is unknown whether the clinical features of TBII-positive patients are different from those of TBII-negative patients. Methods: To evaluate the prevalence of TBII-negative Graves' patients and its clinical differences from TBII-positive patients, we examined TBII by radioreceptor assay in 686 consecutive untreated Graves patients. We found 84 TBII-negative patients(15 men and 69 women, mean age ±EM: 40.9±.4 years) and compared their clinical characteristics with 87 TBII-positive patients (22 men and 65 women, mean age±EM: 39.9±.5 years) who were selected randomly from the same patients group. Results: In this study, TBII was undetectable in 12.2% of patients with Graves' disease(84 of 686). TBII-negative group had a less weight loss than TBII-positive group. However, there was no significant differences in age, sex ratio, prevalence of ophthalmopathy, duration of illness and positive rate of family history for thyroid diseases between TBII-negative and