Association Between Peripheral Thyroid Hormone Sensitivity and Hypertriglyceridemia in Euthyroid Population

Objective We aimed to investigate the correlation between peripheral thyroid hormone sensitivity and hypertriglyceridemia in euthyroid population. Methods A total of 833 individuals who underwent physical examinations were randomly selected. Biochemical parameters including thyroid hormones, liver and kidney functions, blood glucose, and blood lipids were measured. Peripheral thyroid hormone sensitivity was assessed by the ratio of free triiodothyronine to free thyroxine (FT3/FT4). The data were analyzed for the relationship between peripheral thyroid hormone sensitivity and triglyceride (TG). Results smooth curve fitting and threshold effect analysis showed that FT3/FT4 ratio was a positive correlation with TG before the inflection point at 0.426 (β=1.752, P <0.001). Tests for trend in multiple regression equations showed that with the increase of the quartiles of FT3/FT4 ratio, the gradually increasing trend of TG was statistically significant. For per SD increase in FT3/FT4 ratio, TG increased by 0.0587mmol/L (β=0.0587, P =0.001). Subgroup analysis revealed that in female group (β=1.9040, P <0.001), age <65 years group (before the inflection point 0.4272, β=1.7773, P <0.001), and BMI<28 kg/m ² group (β=1.4660, P <0.001), the FT3/FT4 ratio was positively correlated with TG. Conclusion Increased peripheral thyroid hormone sensitivity, as reflected by an elevated FT4 to FT3 conversion rate, is associated with increased TG level in euthyroid population. This association is particularly pronounced in females, individuals with aged<65 years, and non-obese (BMI<28 kg/m ² ) individuals.