Association of thyroid function and thyroid hormone sensitivity with all-cause and cardiovascular mortality in euthyroid patients with MASLD.

Aim of the study: To prospectively investigate the association of individual thyroid function and sensitivity with cardiovascular and all-cause mortality in adult euthyroid patients with metabolic dysfunction-associated steatotic liver disease (MASLD). Material and methods: Data for the study came from 1198 MASLD participants with normal thyroid function in the National Health and Nutrition Examination Survey (NHANES 2007-2012). The Thyroid-Stimulating Hormone Index (TSHI), Thyrotroph T4 Resistance Index (TT4RI), and Thyroid Feedback Quantile-based Index (TFQI Results: During a median follow-up of 11.1 years (12,188.8 person-years), 178 (14.9%) all-cause deaths were recorded, of which 46 (3.8%) were cardiovascular deaths. After adjusting for multiple factors, such as demographic characteristics, lifestyle, economic and social factors, and blood indices, free thyroxine (FT4) was independently correlated with all-cause mortality, and the risk of all-cause mortality increased by 16.2% for each unit increase in FT4 (95% CI: 1.044-1.293). For every one-unit increase in FT4, the risk of all-cause death was increased by 35.3% (95% CI: 1.168-1.567). Furthermore, when stratified by age, sex, race, body mass index (BMI), hypertension, and diabetes, the results were not uniformly significant. Conclusions: In MASLD patients with normal thyroid hormones, higher FT4 levels were significantly associated with increased risk of all-cause mortality, while higher FT4 levels were significantly linearly associated with cardiovascular mortality.