Hypothyroidism and cardiovascular disease: role of new risk factors and coagulation parameters

Hypothyroidism is a common condition and recent epidemiological studies demonstrated that up to 10 percent of subjects may display its subclinical form. Despite the well-known relationship between overt hypothyroidism and cardiovascular disease, few studies demonstrating such a link are available. However, the relationship between hypothyroidism and a variety of cardiovascular risk factors is now well established. Recent data on new cardiovascular risk factors that were shown to be associated with hypotyroidism are reviewed. Haemostatic and fibrinolytic parameters are disturbed differently according to the stage of hypothyroidism. C-reactive protein levels are higher in patients with overt and subclinical hypotyroidism compared to euthyroid patients. In contrast, elevation of homocysteine values was demonstrated only in overt hypothyroidism. Although no randomized controlled trial evaluated the potential benefits of levothyroxine substitution on the risk to suffer major coronary events in patients with subclinical hypothyroidism, there is growing evidence that this disorder is mainly characterized by a high risk of cardiovascular disease.