Abstract
Resistance to thyroid hormone syndrome (RTH) is an autosomal dominant or recessive genetic disease caused by mutation of either the thyroid hormone receptorβ (THR-β) gene or the thyroid hormone receptorα (THR-α) gene. RTH due to mutations of the THR-β gene (hereafter, RTH-β) is characterized by a decreased response of the target tissue to thyroid hormone, increased serum levels of free triiodothyronine (FT3) and/or free thyroxine (FT4), and inappropriate secretion of thyroid-stimulating hormone (TSH, normal or elevated). Clinical manifestations of RTH-β vary from hyperthyroidism to hypothyroidism or simple goiter, and RTH-β is often misdiagnosed clinically. The present review was prepared for the purpose of expanding knowledge of RTH-β in order to reduce the rate of misdiagnosis.