What is the Origin of Acquired Thyroid Resistance?

The concept is rooted in clinical endocrinology, classifying non-responsiveness to thyroid hormone into a category developed over time, distinguishing it from rare, inherited genetic resistance syndromes. It defines a failure of the endocrine system's peripheral component to properly interpret the thyroid signal.

What is the Mechanism of Acquired Thyroid Resistance?

The underlying process often involves modulations at the cellular level, including impaired transport of T4 or T3 into the target cell, or functional defects in the nuclear Thyroid Hormone Receptor (TR). Chronic non-thyroidal illness, certain pharmacological agents, or severe metabolic stress can induce changes in deiodinase enzyme activity or coregulator protein recruitment. These factors effectively diminish the downstream gene transcription and metabolic regulation normally driven by thyroid hormone.

Acquired Thyroid Resistance ∞ Area

Acquired Thyroid Resistance

Meaning

Acquired Thyroid Resistance describes a physiological condition where peripheral target tissues demonstrate a reduced sensitivity to the metabolic and regulatory actions of thyroid hormones, specifically triiodothyronine (T3) and thyroxine (T4). Circulating levels of T3 and T4 may be normal or even elevated, yet the body displays symptoms consistent with hypothyroidism. This resistance represents a functional decoupling of the hormonal signal from the cellular response.