Abstract
Subclinical hypothyroidism (HSC) is a relatively common thyroid dysfunction, characterized by the increase of the thyroid stimulating hormone (TSH) in the presence of normal free thyroxine values. Thyroid hormones are known for the cardiovascular effects, and the consequences of HSC on the cardiovascular system have become the focus of many studies lately. There are clear indications of the relationship between HSC and cardiovascular risk factors such as hypertension, dyslipidemia and atherosclerosis; also, HSC is associated with metabolic syndrome, BMI increase and cardiac insufficiency. Therefore, many clinical trials investigate the benefits and risks of HSC treatment with L-thyroxine.