Thyrotropin receptors, thyroid hormones and thyroglobulin in patients with Hashimoto's thyroiditis

TSH receptors in plasma membranes of thyroid nodular and perinodular tissue and the concentration of thyroid hormones and thyroglobulin in serum were estimated in patients with Hashimoto's thyroiditis (HT) and in six persons with scintigraphically cold thyroid nodules (AFN). In perinodular tissue of HT patients specific binding of 125I-bTSH was found to be significantly decreased (1.50 +/- 0.13%; mean +/- S.E.) as compared with AFN patients (2.79 +/- 0.53%), whereas any significant difference in hormone binding to nodular tissues between both examined groups was not detected. Scatchard analysis of TSH binding revealed two kinds of binding sites for both thyroid tissues of all examined patients. The capacity of high affinity binding sites in both thyroid tissues of HT patients was found to be decreased (3.92 +/- 0.86 fmol/mg protein in nodular tissue and 5.93 +/- 1.16 fmol/mg protein in perinodular tissue) in comparison with these tissues of AFN patients (18.80 +/- 18.36 and 32.24 +/- 33.38, respectively). Any differences in dissociation constant and capacity of low affinity binding sites between analysed groups were not observed. Serum TSH levels of HT patients were higher than these in AFN patients and were not significantly changed after surgical treatment. Any difference in triiodothyronine (T3) levels between analysed groups was not detected, while the concentration of thyroxine (T4) was lower in HT than in AFN and significantly decreased after the excision of thyroid gland. Thyroglobulin levels were significantly changed after surgical treatment in both analysed groups.