Abstract
BACKGROUND: Obesity is an established contributor to hepatic steatosis. Despite weight control efforts, the incidence of steatosis and its associated hepatic complications continues to increase, highlighting the critical need to identify obesity-related pathogenic mechanisms for developing effective therapeutic strategies. AIM: This study aims to explore the association between thyroid hormone sensitivity indicators and hepatic steatosis assessed by controlled attenuation parameter (CAP) values in euthyroid individuals with overweight/obesity. METHODS: Sensitivity to THs, was evaluated using TFQI(FT3), TFQI(FT4), TSHI, TT4RI, TT3RI, and FT3/FT4 ratio. Hepatic steatosis was diagnosed via Vibration-controlled Transient Elastography (VCTE). Linear regression, binary logistic regression, and restricted cubic spline regression (RCS) were used to analyze the associations between these composite indices and CAP levels. Bayesian mediation analysis was performed to assess the mediation effect of liver enzymes and lipids on the relationship between sensitivity parameters to THs and CAP. RESULTS: Compared to the non-severe hepatic steatosis group, the severe hepatic steatosis group exhibited significantly higher levels of TFQI(FT3), and FT3/FT4 ratio (all P < 0.05). After adjustment for multiple risk factors, TFQI(FT3) (β = 25.38, 95% CI 10.21–40.55) and the FT3/FT4 ratio (β = 210.92, 95% CI 116.37–305.47) increased with CAP (P<0.001), but not in TFQIFT4 (p = 0.071). These associations remained significant in binary logistic regression analysis and RCS. Further mediation analysis and subgroup analysis showed that the correlation was not mediated by blood lipid and liver enzyme impairment, and remained stable across all subgroups. CONCLUSION: The correlation between TH sensitivity and hepatic steatosis was significantly stronger in TFQI(FT3) than in TFQI(FT4). TFQI(FT3) and the FT3/FT4 ratio can be used as new indicators for predicting hepatic steatosis in individuals with overweight/obesity.