It is hypothesized that this conversion of proactive T4 into active T3 is decreased in the liver of patients with NASH, suggesting the critical role of T3 in NAFLD/NASH [22]. The effects of T3 peripherally are mediated through two subtype receptors, thyroid hormone receptor-α (THR-α) expressed in the heart, brain, and skeletal muscle and Thyroid Hormone Receptor-β (THR-β) expressed in the liver. This evidence concerns the gene THRB and metabolic dysfunction-associated steatohepatitis.