Serum Thyroid Hormones Levels are Significantly Associated with Nonalcoholic Fatty Liver Disease in Euthyroid Chinese Population

Background: Thyroid hormones play an essential role in metabolic homeostasis. Previous studies have demonstrated a close relationship between thyroid abnormalities and metabolic disorders. This retrospective cross-sectional study was to investigate whether significant differences of circulating thyroid profiles exist and to explore the potential of serum thyroid hormones in reflecting advanced fibrosis in subjects with Nonalcoholic Fatty Liver Disease (NAFLD). Methods: Abdominal ultrasonography was performed to diagnose NAFLD. For all the participants including 522 NAFLD patients and 415 gender- and age-matched controls recruited, demographic, clinical data and thyroid functions were recorded. Fasting serum thyroid hormones including free triiodothyronine (FT3), free thyroxine (FT4), total thyroxine (TT4), total triiodothyronine (TT3), and thyroid-stimulating hormone (TSH) were evaluated. Results: Serum FT3 levels in subjects with NAFLD were significantly reduced, while TSH was increased compared to that in controls. The NAFLD subjects with metabolic syndrome (MS) had significantly lower FT3 and FT4 levels and higher TSH levels than the non-MS group. Serum TSH levels were positively associated with the risk for NAFLD, while FT3 levels were inversely correlated with NAFLD. Among thyroid hormones, low serum FT4 was the only independent predictor of reflecting advanced fibrosis in NAFLD participants. Conclusions: An altered thyroid profile not only can be significantly associated with an increased incidence of NAFLD, but also had clinical predictive value for assessing significant fibrosis.