Benefits of Levothyroxine Replacement Therapy on Nonalcoholic Fatty Liver Disease in Subclinical Hypothyroidism Patients

Objectives. To evaluate the effect of levothyroxine (LT(4)) replacement therapy on nonalcoholic fatty liver disease (NAFLD) in subclinical hypothyroidism (SCH) patients. Methods. This study was a post hoc analysis of a randomized controlled trial and involved 33 significant and 330 mild SCH patients. All of the significant SCH patients received LT(4) supplement. The mild SCH patients were grouped as LT(4) treated or not. After 15 months of follow-up, prevalence of NAFLD in each group was reevaluated. Subgroup analysis was conducted in mild SCH patients with dyslipidemia. Results. After treatment with LT(4), the prevalence of NAFLD in significant SCH patients reduced from 48.5% to 24.2% (p = 0.041). In mild SCH patients, prevalence of NAFLD and serum alanine aminotransferase (ALT) was not significantly affected by LT(4) supplementation. Nonetheless, mild SCH patients with dyslipidemia who received LT(4) treatment experienced decreases in the prevalence of NAFLD and serum ALT levels (p < 0.05 for both). In contrast, these parameters remained comparably stable in patients who were not treated. Conclusion. LT(4) supplementation has benefits on NAFLD in significant SCH patients or mild SCH patients with dyslipidemia. For NAFLD patients with SCH, appropriate supplementation of LT(4) may be an effective means of controlling NAFLD. The original trial was registered with ClinicalTrials.gov (NCT01848171).