Thyroid and cardiovascular diseases.

The thyroid gland is one of the major regulator organs of hemostasis in the human body, controlling the functioning of numerous systems. Thyroid hormones exert a modulating effect on the cardiovascular system in particular, ensuring optimal functioning within the normal range. Triiodothyronine (T3), as an active form of thyroid hormone, is mainly responsible for this effect via both genomic and nongenomic mechanisms. It has been reported that overt thyroid disorders are associated with a number of cardiovascular diseases and cardiac mortality. While hyperthyroidism appears to be related to atrial fibrillation and heart failure, the most pronounced cardiovascular complication of hypothyroidism seems to be atherosclerosis. Achieving euthyroidism is of great importance for restoring cardiovascular function. However, depending on the underlying health conditions, this may not be possible for all patients. Furthermore, there has been a growing focus on the role of subclinical thyroid dysfunctions and their impacts on the cardiovascular system in recent years. The pattern of cardiovascular abnormalities in subclinical thyroid disorders appears to parallel that of overt hypothyroidism, suggesting that even mild alterations in thyroid hormone levels may also have effects on the cardiovascular system. The management of subclinical thyroid disease remains controversial. Current evidence suggests that patient age and underlying cardiovascular diseases are major factors in clinical decision-making.