A Phase 3 Trial of Resmetirom in NASH with Liver Fibrosis

To the Editor: Harrison et al. (Feb. 8 issue) 1 found that resmetirom treatment reduced levels of free thyroxine (FT4) by approximately 16 to 19% in patients with nonalcoholic steatohepatitis (NASH). An increase in the levels of type 1 deiodinase (DIO1) that was due to thyroid hormone receptor beta–selective agonism may have contributed to the decrease in FT4 levels. 2 However, increased DIO1 function is associated not only with decreased FT4 levels but also with increased levels of free triiodothyronine (FT3). 3 The fact that FT3 levels did not increase with resmetirom therapy suggests that central suppression of the hypothalamic–pituitary–thyroid axis is likely . . .