Having an overactive thyroid gland is linked with an increased risk for atrial fibrillation (a type of abnormal heart rhythm), but neither an over- or under active thyroid gland is associated with a higher risk for other cardiovascular problems or increased risk of death, according to a study in the March 1 issue of JAMA: The Journal of the American Medical Association.
Thyroid hormone excess and deficiency are common, and can be readily diagnosed and treated. Previous studies have suggested that abnormal levels of thyroid stimulating hormone (TSH) may represent a cardiac risk factor. Cardiovascular diseases (CVD) are the most common cause of death in the U.S. Even mildly altered thyroid status reportedly affects serum cholesterol levels, heart rhythm and rate, ventricular function, risk of coronary artery disease, and cardiovascular death. However, the relationship between abnormal thyroid function and cardiovascular outcomes remains unclear, according to background information in the article.
Anne R. Cappola, M.D., Sc.M., of the University of Pennsylvania School of Medicine, Philadelphia, and colleagues tested the hypothesis that abnormal thyroid status is associated with increased cardiovascular risk and death in individuals with unrecognized thyroid dysfunction. The study included 3,233 U.S. individuals aged 65 years or older who had their serum thyroid-stimulating hormone levels measured when enrolled in 1989-1990. The cardiovascular health of the patients, who were not taking thyroid medication, was assessed through June 2002.