[Secretion of TSH and stimulation-ability of the hypophysis after long-term suppression therapy in euthyroid nodular goiter and residual thyroid gland after subtotal resection of goiter].

In 51 patients, 33 with euthyroid goiter and 18 after subtotal thyroidectomy, plasma concentrations of T4, T3, and TSH before and after stimulation with TRF were determined under long term suppression with thyroid hormone and 1,2, and 4 weeks after stopping it. Even after complete suppression (delta TSH less than 0, 5 muU/ml) resumption of TSH secretion occurred within 4 weeks in all but two. A significantly higher increase of TSH and somewhat lower thyroid-hormone concentrations turned out in operated patients. An excessive decrease of T3 (and T4) concentrations within the 1st (and 2nd) week after therapy, dependent on the degree of previous TSH suppression, could be due to transitory thyrotropic insufficiency.