Addressing Cardiovascular Risks in Thyroid Disorders

Disorders of the thyroid gland usually involve the failure to produce enough thyroid hormone (hypothyroidism) or the production of too much (hyperthyroidism). Approximately 4.6% of the American population has hypothyroidism and 1.3% has hyperthyroidism. Graves disease, an autoimmune disorder, is the most common cause of hyperthyroidism, with other causes including toxic multinodular goiter and toxic adenoma. Over the last 30 years, numerous clinical studies have shown that thyroid disorders are associated with an increased risk for manifestations of coronary heart disease (CHD) as well as higher rates of cardiac events, cardiovascular disease (CVD)-related death, and all-cause mortality. For those with existing CVD, disorders of the thyroid gland can worsen old cardiac symptoms or cause new ones. These disorders can accelerate the underlying heart problems. A review, published in the August 2010 issue of Nature Reviews: Endocrinology, compared the cardiovascular risks associated with these disorders. Subclinical Thyroid Disease Subclinical hyperthyroidism is a mild form of hyperthyroidism that is diagnosed by abnormal blood levels of thyroid hormones, often in the absence of any symptoms. Subclinical hypothyroidism, also called mild thyroid failure, is diagnosed when peripheral thyroid hormone levels are within normal reference laboratory range but serum thyroid-stimulating hormone (TSH) levels are mildly elevated. This condition occurs in 3% to 8% of the general population. Subclinical hypothyroidism, the most prevalent form of thyroid diseases, is more common in females and its prevalence increases with age, affecting up to 20% of women over the age of 60. Of patients with subclinical hypothyroidism, 80% have a serum TSH of less than 10 mIU/L. With subclinical hypothyroidism, there is a high likelihood of progression to...