Associations Between Thyroid Hormones,TSH And Carotid Artery Intima-media Thickness In Euthyroid Subjects

ObjectivesAtherosclerosis is a common disease of vascular. With the rapid development of aging population in the modern society, the disease has become the leading cause of death not only among the elderly, but also in all the people throughout the world. Although the mechanism of atherosclerosis have not exactly elucidated, but many researchers from domestic and foreign have found that many factors associated with atherosclerosis. To date,many risk factors such as gender, age, drinking, smoking, hyperlipidemia, hypertension, diabetes mellitus, atrial fibrillation, genetic factors and abnormal distribution of fat have been confirmed associated with atherosclerosis. Recent researches have found that in addition to the traditional vascular risk factors mentioned above, many other factors including thyroid function are also associated with atherosclerosis.In recently, more and more studies have proved that certain degree of abnormality of thyroid function are related to atherosclerosis. A number of studies have found that hypothyroidism or subclinical hypothyroidism are related to the carotid intima-media thickness, and this correlation still exist after the adjustment of blood glucose, lipids, smoking and other factors. Present studies have found that even if the normal thyroid function may be associated with atherosclerosis.1. To explore the relationship between the CIMT and thyroid function.2. To elucidate the association of CIMT and thyroid function after adjustment by the confounding factors including blood lipids, blood glucose and age.MethodsCarotid artery intima-media thickness(CIMT) is an early indicator of atherosclerosis. Doppler ultrasound examination is the effective and non-invasive method we often used to measure the intima-media thickness of the common carotid artery. In this study, we have determined CIMT of 319 subjects with normal thyroid function. All 518 subjects are come from the physical examination center of The Affiliated Hospital of Tai’an Medical College. All clinical characteristics such as age, gender were collected from all subjects, height, weight and blood pressure were measured and body mass index(BMI) were calculated. They all were asked to complete a questionnaire. patients were excluded from the study if they have obvious heart diseases, liver diseases or chronic lung dysfunction.Patients with hypertension, malignant tumor, connective tissue disease, rheumatism, were excluded too.Finally, only 319 subjects were enrolled into the study according to the inclusion criteria, including 196 males(61.4%), 123 females(38.6%).All calculations were performed using the SPSS 18.0 version for Windows. Chi-square analysis was used to test the distribution of gender. Spearman correlation analysis, multiple linear regression model were used to estimate the relationship between CIMT and thyroid hormone. Results1.The serum levels of TSH,LDL were gradually decreased with the increasing level of serum FT3,FT4.2.The serum level of LDL(P=0.041)、TC(P=0.01)levels were gradually increased With the increasing TSH.3.By Spearman correlation analysis TSH was significantly correlated with CIMT(P=0.031), By multivariate linear regression analysis adjusted for age and serum lipid, free thyroxine was significantly correlated with CIMT(P=0.017)4.By multivariate linear regression analysis adjusted for Other risk factors, CIMT was significantly correlated with age(P=0.038)、LDL-C(P=0.039),TC(P=0.047),Log TSH(P=0.017). ConclusionIn this study, we found that serum lipids gradually increased with the increasing of FT3,FT4.TSH was significantly correlated with CIMT.however, we found no correlation between FT3,FT4 and CIMT. Spearman correlation analysis and multivariate linear regression analysis showed that TSH correlated with serum lipids, CIMT. This study suggests that if TSH belongs to a higher level, there may be risk of atherosclerosis in general population with euthyroid status.