Resistance to thyroid hormone.

Resistance to thyroid hormone encompasses a clinically heterogeneous group of conditions characterized by reduced responses of target tissues to a supply of thyroid hormone that under normal circumstances would be excessive. The syndrome of resistance to thyroid hormone is first suspected when serum thyroid hormone levels are found to be elevated in the presence of nonsuppressed serum thyrotropin (TSH). Clinical confirmation of the diagnosis requires the demonstration of the failure of full replacement doses of thyroid hormone to produce the expected suppressive effect on the secretion of TSH and a failure to induce appropriate responses in peripheral tissues.