[Dynamics of changes in the concentration of thyroid hormones in in rat blood after subtotal thyroidectomy, internal,...

Thyroidectomy or administration of high activities (> 1.1 Mbq) of 131I to rats causes initial decrease in blood concentration of thyroid hormones which returns to the normal level. Administration of lower doses (< 1.1 Mbq) of radioactive iodine or external radiation (1, 3, 6 Gr) did not cause similar changes. Data obtained that: 1) thyroid gland is relatively radioresistant organ with high reparative function after surgical or radioactive damage; 2) alterations of thyroid status after the external radiation are not related to a direct action of radiation on the thyroid gland.