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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...

Managing Thyroid Disease During Pregnancy

The effects of pregnancy on the thyroid gland are profound. The gland is required to produce a 50% increase in thyroxine (T4) and triiodothyronine (T3). While a healthy thyroid should respond well to pregnancy, women with limited thyroidal reserve or iodine deficiency who become pregnant can develop hypothyroidism. “Women in high-risk groups need to be tested as early as possible for hypothyroidism during the first trimester.” Knowledge about the interaction between the thyroid gland and pregnancy has exploded over that last 15 to 20 years. In response to the emerging data, the American Thyroid Association (ATA) recently created clinical guidelines on the diagnosis and treatment of thyroid disease during pregnancy and postpartum. They were published in the October 2011 issue of Thyroid. Pregnancies At-Risk for Thyroid Disease According to the ATA guidelines, about 10% of pregnant women are thyroid peroxidase (TPO)-antibody positive but have normal thyroid function. These women have a two- to four-fold increased risk of miscarriage when compared with women who don’t have the antibody. Among women without the antibody but with slightly elevated thyrotropin (TSH) levels, the risk of miscarriage is increased by 60% when compared with women without hypothyroidism. Women with either the TPO antibody or mild hypothyroidism are also at risk for preterm delivery. The 10% of all women who are TPO-antibody positive have a 50% chance of developing postpartum thyroiditis. Thyroid Screening Recommendations Women in high-risk groups need to be tested as early as possible for hypothyroidism during the first trimester, according to the ATA guidelines. These groups include (but are not limited to) women: With a history of thyroid dysfunction or prior thyroid...
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