Thyroid Research Thyroid Research Archive Hyperthyroidism

Thyrotropin-like antibodies may inhibit thyrotropin secretion

(November 2003)

The background of the study. Thyrotropin (TSH) secretion is low in patients with hyperthyroidism, and it may remain low for weeks or even months after the patients are treated. In patients with hyperthyroidism caused by Graves' disease, the TSH-like antibodies that stimulate the thyroid (known as TSH receptor-stimulating antibodies), and therefore cause hyperthyroidism, may contribute to this inhibition. This study tested this possibility by relating TSH secretion to the serum concentration of TSH-like antibodies in patients with Graves' hyperthyroidism during antithyroid drug therapy.

How the study was done. The study subjects were 45 patients with hyperthyroidism caused by Graves' disease who were treated with an antithyroid drug. After they had normal thyroid function for several months, serum TSH and TSH-like antibodies were measured.

The results of the study. All patients were well and had normal serum thyroid hormone concentrations after treatment for an average of 7 months. At that time, serum TSH-like antibody values were normal in 25 patients and high in 20 patients. The patients who had normal serum TSH-like antibody values had higher serum TSH concentrations (mean, 0.8 mU/L) than did the patients with high serum antibody values (mean, 0.09 mU/L).

The conclusions of the study. In patients with Graves' hyperthyroidism, continued production of TSH-like antibodies may cause continued inhibition of TSH secretion.

The original article. Brokken LJ, Wiersinga WM, Prummel MF. Thyrotropin receptor autoantibodies are associated with continued thyrotropin suppression in treated euthyroid Graves' disease patients. J Clin Endocrinol Metab 2003;88:4135-8.