Inflammation is at the core of most chronic illnesses including hypothyroidism and Hashimoto’s disease. But how exactly does inflammation cause hypothyroidism? Nonthyroidal illness syndrome (NTIS) is the state in which inflammation causes negative changes to thyroid hormone including low T3 and increased reverse T3 (rT3). T3 is the most active form of thyroid hormone and rT3 actually blocks T3 receptors so inflammation can really knock out thyroid function. TSH levels however stay relatively “normal” in NTIS thus leaving many patients with the symptoms of hypothyroidism but no diagnosis since no one is checking their T3 or rT3 levels.
In this article I’ll be referencing a paper entitled, “IL-6 promotes nonthyroidal illness syndrome by blocking thyroxine activation while promoting thyroid hormone inactivation in human cells.”