Reverse T3 in patients with hypothyroidism on different thyroid hormone replacement.

ABSTRACT:

Background

Reverse T3 (rT3) is a biologically inactive form of T3 (triiodothyronine), a thyroid hormone, that is created by peripheral 5 deiodination of T4 (thyroxine) by type 1 and type 3 deiodinase enzymes (D1 and D3 respectively) and may block T3 binding to the thyroid hormone receptor. Approximately 15% of patients on L-T4 replacement therapy with a normalized thyroid-stimulating hormone (TSH) report experience continued fatigue and other hypothyroid symptoms; therefore, efforts are needed to understand why this occurs and how it can be corrected. Decades ago, endocrinologists realized that in patients with severe illnesses, rT3 is typically high and T3 is typically low; this was termed "euthyroid sick syndrome". More recently, functional medicine and other doctors, have argued

SUBMITTER: Wilson JB 

PROVIDER: S-EPMC12148341 | biostudies-literature | 2025

REPOSITORIES: biostudies-literature