Noriyo Sayama

Role of thyroid-stimulating blocking antibody in patients who developed hypothyroidism within one year after 131I treatment for Graves' disease.

We recently reported that thyroid‐stimulating blocking antibody (TSBAb) may not contribute to the development of hypothyroidism more than six years after 131I treatment. In the present study, we attempted to determine whether hypothyroidism that develops within a shorter period of time following 131I therapy is associated with TSBAb.

Relationship between thyroid-stimulating antibodies and thyrotropin-binding inhibitory immunoglobulins years after administration of radioiodine for Graves’ disease: retrospective clinical survey

Thyroid-stimulating antibody (TSAb) activity and the TSH-binding inhibitory immunoglobulin (TBII) index were assessed in 158 patients with Graves’ disease who had been treated with 131I 6–14 years earlier. Twenty-one patients (13%) were still hyperthyroid, 45 (28%) were euthyroid, 44 (28%) were subclinically hypothyroid, and 48 (30%) were overtly hypothyroid. Positive results were obtained in 10 (48%) of the 21 patients with hyperthyroidism for both TSAb and TBII assays, and in 3 patients (14%) in one of the assays. In contrast, only two (5%) patients with subclinical hypothyroidism and 1 (2%) patient with overt hypothyroidism tested positive in both assays, and 11 (25%) subclinically hypothyroid patients and 15 (31%) overtly hypothyroid patients tested positive in one of the assays. The correlation coefficients between TSAb and TBII were 0.88 (p<0.01) in hyperthyroid patients, 0.49 (p<0.01) in euthyroid patients, 0.34 (p<0.05) in subclinically hypothyroid patients, and 0.12 (p>0.05) in patients with overt hypothyroidism. Findings indicate the presence of long-term changes in the population of TSH receptor antibodies years after 131I treatment, which may influence thyroid function.