title: Increased thyrotropin binding in hyperfunctioning thyroid nodules.
abstract: The object of this study was to investigate TSH receptors in hyperfunctioning thyroid nodules (HFN). In HFN, obtained from seven patients, 125-I-TSH binding as determined by equilibrium binding analysis on particulate membrane preparations, was found to be significantly increased as compared with normal thyroid tissues (five patients; P less than 0.001). Scatchard analysis of TSH-binding revealed two kinds of binding sites for both normal thyroid tissue and HFN, and displayed significantly increased association constants of high- and low-affinity binding sites in HFN (Ka = 11.75 +/- 6.8 10(9) M-1, P less than 0.001 and Ka = 2.1 +/- 1.0 10(7) M-1, P less than 0.025; x +/- SEM) as compared with normal thyroid tissue (Ka = 0.25 +/- 0.06 10(9) M-1, Ka = 0.14 +/- 0.03 10(7) M-1; x +/- SEM). The capacity of the high-affinity binding sites in HFN was found to be decreased (1.8 +/- 1.1 pmol/mg protein, x +/- SEM) in comparison with normal thyroid tissue (4.26 +/- 1.27 pmol/mg protein; x +/- SEM). TSH-receptor autoradiography applied to cryostatic tissue sections confirmed increased TSH binding of the follicular epithelium in HFN. These data suggest that an increased affinity of TSH-receptor sites in HFN in iodine deficient areas may be an important event in thyroid autonomy.
authors: Nuklearmedizinische Abteilung, Universität Hamburg, Germany.
authors: H W
authors: HW
authors: Müller-Gärtner
authors: C
authors: C
authors: Schneider
authors: V
authors: V
authors: Bay
authors: A
authors: A
authors: Tadt
authors: W
authors: W
authors: Rehpenning
authors: K
authors: K
authors: de Heer
authors: M
authors: M
authors: Jessel
mesh_terms: D006801:Humans; D006980:Hyperthyroidism / Q000378:metabolism*; D011989:Receptors, Thyrotropin / Q000378:metabolism*; D013961:Thyroid Gland / Q000378:metabolism*; D013972:Thyrotropin / Q000378:metabolism*
chemical_list: D011989:Receptors, Thyrotropin; D013972:Thyrotropin