Physiologic thyroid activation in normal early pregnancy is induced by circulating hCG.

摘要: In normal early pregnancy, serum free thyroxine (T4) increases and TSH decreases, indicating that the thyroid gland is activated physiologically. To identify factor responsible for this activation, we measured thyroid-stimulating activity in comparison with level of hCG 39 women pregnancy. Serum was by a sensitive cyclic adenosine 3',5'-monophosphate (cAMP) accumulation assay using rat cell line (FRTL-5). Thyroid-stimulating detected 37 (95%), activities individuals correlated positively their T4 levels (r = 0.474; P less than .01) negatively -0.376; .02). Moreover, closely 0.741; .001), but completely abolished pre-treatment sera antibodies. These data indicate physiologically hCG, which has intrinsic activity.