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Functional Thyroid Resistance

Meaning

Functional Thyroid Resistance describes an acquired or non-genetic state of reduced cellular responsiveness to the active thyroid hormone, triiodothyronine (T3), at the level of the target cell receptor or post-receptor signaling cascade. Unlike the rare congenital Resistance to Thyroid Hormone (RTH) syndrome, this functional variant is thought to be driven by chronic physiological stressors and environmental factors. It results in a clinical picture of hypothyroidism in specific tissues despite seemingly normal or adequate circulating T3 levels.