The role of free triiodothyronine in high-density lipoprotein cholesterol metabolism

The aim of this study was to analyze the correlation between free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), and serum high-density lipoprotein cholesterol (HDL-C), and to explore the significance of FT3 in HDL-C metabolism in people with normal thyroid function. A total of 461 Chinese, aged ≥28 years, from a college community in Nanning, Guangxi, were enrolled for a cross-sectional epidemiological investigation of metabolic syndrome from October 2016 to November 2016. Height, weight, blood pressure, total cholesterol, HDL-C, triglyceride (TG), fasting glucose (FPG), FT3, FT4, and TSH were measured for each individual. Multiple linear regression analysis was used to evaluate the correlation between FT3, FT4, TSH, and HDL-C. After controlling for sex, age, body mass index (BMI), smoking, drinking, and other confounding factors, FT3 was negatively correlated with HDL-C levels, on average, when FT3 increased by 1 pmol/L, HDL-C decreased by 0.143 mmol /L with a statistically significant difference (P < .001). FT4 was positively correlated with HDL-C, and HDL-C increased by 0.016 mmol/L for every 1-pmol/L increase in FT4. TSH was negatively correlated with HDL-C, and HDL-C decreases by 0.010 mmol/L for every 1-μIU/mL increase in TSH, but the differences were not statistically significant (P > .05). FT3 may be an important factor affecting HDL-C levels. The detection and regulation of thyroid hormone (especially FT3) in patients with low HDL-C, as well as the detection of HDL-C in patients with thyroid dysfunction, is important to prevent the occurrence of cardiovascular diseases.