Effects Of Thyroid-stimulating Hormone On The Risk Of Developing Atherosclerosis In Subclinical Hypothyroidism

Objective: The aim of our study was to assess the potential role of thyroid-stimulating hormone(TSH) in the risk of developing atherosclerosis in subclinical hypothyroidism(SCH).Materials and methods: 240 SCH patients and 150 euthyroid volunteers were recruited for the study. SCH patients were stratified into two groups according to TSH levels(group A: TSH< 10 m IU/L; group B: TSH>10 m IU/L). All subjects were examined for clinical and biochemical parameters. Visfatin, omentin-1 and circulating endothelial biomarkers including nitric oxide(NO), endothelin(ET-1), thromboxane( TXA2) and prostacyclin(PGI2) were measured. Patients in group B received L-thyroxine replacement to achieve euthyroidism; after 6 months of euthyroidism all measurements were repeated.Results: Patients with SCH had higher total cholesterol(TC), C-reactive protein(CRP)and low-density lipoprotein cholesterol(LDL-C) levels and lower nitric oxide(NO) and omentin-1 levels compared to euthyroid subjects(all P< 0.05). TC and LDL-C decreased significantly, while NO and omentin-1 levels increased significantly after L-thyroxine replacement. Based on multivariate liner stepwise regression analysis, omentin-1 was independently correlated with BMI and TSH; NO was independently correlated with age, TSH, LDL-C and omentin-1.Conclusions: High TSH level contributes to endothelial dysfunction in SCH, while TSH-induced decrease of omentin-1 provides a new link between SCH and atherogenic risk.