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Thyroid Hormone Resistance

Meaning

Thyroid hormone resistance (THR) is a rare clinical syndrome characterized by a reduced responsiveness of target tissues to the action of thyroid hormones, specifically T3 and T4, despite having normal or elevated circulating levels of these hormones. This condition is typically caused by genetic mutations in the thyroid hormone receptor beta ($text{TR}beta$) gene, resulting in a defective receptor that cannot effectively transduce the hormonal signal. The clinical presentation is highly variable, ranging from mild symptoms to features of both hypothyroidism and hyperthyroidism simultaneously.