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Hypothyroidism & Heart Disease

Hypothyroidism is a deficiency in thyroid hormone that can be caused by disease in the thyroid gland itself or by a drop in the production of thyrotropin-stimulating hormone (TSH) in the pituitary gland, according to HealthScout. Long recognized as a possible precursor to heart disease, hypothyroidism's relationship to various cardiovascular risk factors has been the subject of numerous studies in recent years.

  1. Cholesterol and Homocysteine

    • High levels of blood cholesterol, particularly low-density lipoproteins, the so-called bad cholesterol, and the amino acid homocysteine have been associated with full-blown hypothyroidism for decades. More recent studies also have established a relationship between early-stage, or subclinical, hypothyroidism and elevated cholesterol and homocysteine readings. High readings of both these substances increase the risk of coronary heart disease. More than 90 percent of patients with either overt or subclinical hypothyroidism have excessive levels of cholesterol and/or homocysteine in their blood, compared with roughly a third of the general public.

    Impact on Metabolism

    • Proper thyroid function is closely related to a healthy metabolism. In turn, optimal metabolic function helps to rid the body of elevated levels of both cholesterol and homocysteine, both of which are associated with increased risk of heart disease. By definition, hypothyroidism represents an underactive thyroid function, accounting for the buildup of both cholesterol and homocysteine .

    Cardiac Pump Performance

    • Studies published in the Journal of the American College of Cardiology in 2003 and 2005 point to a link between hypothyroidism and compromised cardiac pump performance. According to MyThyroid.com, both studies conclude that the correction of even subclinical hypothyroidism may result in improved cardiac function. Another study, this one published in the June 1, 2003, issue of the Journal of Clinical Endocrinology & Metabolism, observed that short-term treatment with thyroid hormone may produce improvements in several indicators of cardiac function. While acknowledging these positive reports, MyThyroid.com cautions that it is best to take a conservative approach to the treatment of hypothyroidism, beginning with relatively low dosages of thyroid hormone.

    Other Causes

    • Besides thyroid disease and abnormally low levels of TSH, hypothyroidism may be caused by a host of other factors. According to MayoClinic.com, these include side effects from treatment for hyperthyroidism, an overactive thyroid gland; radiation therapy; and side effects from a handful of medications, including lithium, which is used to treat some psychiatric disorders.

    High-Risk Groups

    • Those at increased risk of hypothyroidism, according to MayoClinic.com, include pregnant women, patients with an iodine deficiency, people with a family history of autoimmune disorders, females over the age of 50, and those who have taken antithyroid or radioactive iodine medications.

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