Independent Associations of Thyroid-Related Hormones with Hepatic Steatosis and Insulin Resistance in Euthyroid Overweight/Obese Chinese Adults

Purpose: The aim of the study is to explore the independent association of free triodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) with hepatic steatosis and insulin resistance. Methods: A cross-sectional study of 88 overweight/obese adults who underwent anthropometric measurements (BMI, waist circumference (WC) and waist-to-height ratio (WHtR)), hepatic steatosis assessment (FibroScan) and thyroid-related hormones tests was conducted from 2018 to 2020 in Xiamen, China. Results: : Subjects with increasing tertiles of FT3 showed significantly higher levels of controlled attenuation parameter (CAP) ((295.4±44.1, 290.1 ± 68.2 and 331.7 ± 43.6 (dB/m) for tertile 1-3, respectively, p=0.007) and fatty liver index (FLI) score (47.7 (33.9-60.8), 61.5 (45.1-88.9) and 90.5 (84.5-94.8), respectively, p<0.001). FT3 significantly and positively correlated with obesity index (BMI, WC, and WHtR), homeostatic model assessment of insulin resistance (HOMA-IR) and hepatic steatosis (CAP and FLI). Multivariable linear regression analyses with adjustment for potential confounding factors showed FT3 was independently associated with BMI (regression coefficient (β(95%CI): 0.024(0.004-0.043), p=0.020), HOMA-IR (β(95%CI): 0.091(0.007-0.174), p=0.034), CAP (β(95%CI): 25.45(2.59-48.31), p=0.030) and FLI (β(95%CI): 0.121(0.049-0.194), p=0.001). Neither FT4 nor TSH was significantly associated with any indicators of obesity, insulin resistance or hepatic steatosis. Conclusions: Increased FT3, but not FT4 or TSH, was independently associated with higher risks of hepatic steatosis and insulin resistance in euthyroid overweight/obese Chinese adults. Trial registration Registration is not applicable for our study.