The Occurrence of Thyrotropin Binding-Inhibiting Immunoglobulins and Thyroid-Stimulating Antibodies in Patients with Silent Thyroiditis

Abstract

Silent (painless) thyroiditis has been recognized as a clinical entity for over a decade and is characterized by spontaneously resolving thyrotoxicosis. Its etiology is uncertain; however, a few reports have indicated the occurrence of TSH binding-inhibiting immunoglobulins (TBII) and thyroid-stimulating antibodies (TSAb) in some of the patients. The present study was undertaken to evaluate thyroid function and the occurrence of TBII and TSAb and thyroid autoantibodies (antithyroglobulin and antimicrosomal) in 53 patients with silent thyroiditis during the course of their disease. The patients were divided into 2 major groups: I) those who developed transient hypothyroidism and II) those who did not. All patients initially had significantly increased concentrations of serum T4, free T4, and free T3, suppressed TSH levels, and decreased thyroid radioiodine uptake. TBII and TSAb were initially positive in 8 (15.1%) and 10 patients (18.9%), respectively. Forty patients were available for follow-up. TBII was positive in 6 of 24 (25.0%), and TSAb was positive in 8 of 24 (33.3%) of the patients who developed transient hypothyroidism during the course of their disease. Among the patients who did not become hypothyroid at any time, TBII was positive in only 2 of 16 (12.5%), and none of the patients became TSAb positive. The findings indicate that increased TSAb and TBII activity may be detected in patients with silent thyroiditis and, when present, are associated with transient hypothyroidism during the course of the disease.

Measurement of Red Blood Cell Zinc Concentration with Zn-Test Kit: Discrimination between Hyperthyroid Graves' Disease and Transient Thyrotoxicosis.

“…TBII is positive in patients with Graves' disease in 80-90%, but it is also positive in patients with silent thyroiditis in about 15% [12]. Treatment with antithyroid drugs for silent thyroiditis is inappropriate.…”

Thyroid Hemiagenesis with Postpartum Silent Thyroiditis

“…Morita et al (18 ) reported that increased levels of TBIIs and TSAb may be detected in patients with silent thyroiditis who developed transient hypothyroidism during the course of the disease. They mentioned that TBIIs and TSAb were related to the thyroid damage that caused transient hypothyroidism occurring during the course of silent thyroiditis (18).…”

“…Morita et al (18 ) reported that increased levels of TBIIs and TSAb may be detected in patients with silent thyroiditis who developed transient hypothyroidism during the course of the disease. They mentioned that TBIIs and TSAb were related to the thyroid damage that caused transient hypothyroidism occurring during the course of silent thyroiditis (18). Momotani et al (16) reported that serum levels of TBIIs increased and then decreased in the majority of the patients with postpartum thyrotoxicosis irrespective of the courses of the disease.…”

Thyroid Stimulating Immunoglobulin(TSI) in Graves' Disease.

“…[21]. Cases with the co-existence of TSAb and TSBAb [22] and cases in which TSAb activity changed to TSBAb activity after radioisotope treatment in Graves' disease have been reported [23]. These lines of evidence suggest that the biological activity of patient's IgG depends on the differences in amount of TSAb and TSBAb, so that TBII and TS activities in the co-existence of TSAb and TSBAb may be expressed by the following formula.…”