Aim: Thyroid hormones have many effects on the cardiovascular system. May studies have showed that apparent or subclinical hypothyroidism increase the risk of hypertension hyperlipidemia and so lead to atherosclerosis susceptibility. This risk can be reduced by treatment. But, studies on the relationship between thyroid function tests and cardiovascular risk in euthyroid subjects are contradictory. This study was designed to investigate the effect of TSH, free T3, free T4 and Hashimoto thyroiditis on cardiovascular risk factors in euthyroid subjects.
Method: A cross-sectional study of 144 euthyroid drg-free subjects was made. Serum TSH, freeT3, free T4, anti-thyroid antibodies, fasting blood glucose (APG), fasting lipid profile, fasting insulin, C-reactive protein (CRP), asymmetric dimethylarginine (ADMA), ischemia modified albumin (IMA), IMA-edited according to albumine were analysed. HOMA-İR score and LDL/HDL ratio were calculated. Thyroid ultrasonography was performed to all participants. HT was detected in 61 subjects. Analyzes were performed according to 1, 1.5, 2, 2.5, 3, 3.5 and 4 μIU/ml values for TSH.
Results: In all participants, no difference detected according to 1, 2, 3 and 3.5 μIU/ml values for TSH. In subjects with TSH<1.5 μIU/ml, APG, insuline and HOMA-IR were higher (respectively P=0.039, 0.017 and 0.016). In TSH< 2.5 μIU/ml group, CRP was lower (P=0.042), trigliseride was lower at border (P=0.051) and ADMA was higher at border (P=0.055). In TSH <4 μIU/ml group, trigliseride was lower (P=0.009). Negative correlation was detected between free T4 and age (P=0.025, r=−0.188). Free T3, HT and gender were not related with other parameters. Weak positive correlations between İMA, IMA-edited according to albumine with free T4 were determined (P=0.014, r:0.206 ve 0.207).
Conclusion: In participants withTSH<1.5 μIU/ml APG, insuline and HOMA-İR were higher and trigliseride was lower in subjects with TSH<4 μIU/ml. These results were thought that target range for TSH could be 1.54 μIU/ml. Free T4 was negative correlated with age and positive correlated with IMA-edited according to albumine. Thus, free T4 could be an useful marker to determine the cardiovascular risk of euthyroid subjects. The number of participants must be increased for supporting these findings.
Keywords: TSH, free T4, free T3, Hashimoto thyroiditis, ADMA, IMA, IMA-edited according to albumine
18 - 21 May 2019
European Society of Endocrinology