Hypothyroidism has long been recognized as a risk factor for cardiovascular disease. Research published in the Annals of Internal Medicine (2000;132:270–278) suggests that subclinical hypothyroidism and thyroid autoimmunity may also increase cardiovascular risk.
In subclinical hypothyroidism, individuals often do not exhibit obvious symptoms of low thyroid function, yet blood tests indicate reduced thyroid activity. In this study, women with subclinical hypothyroidism had a 70% higher likelihood of aortic atherosclerosis (hardening of the aorta) and more than double the risk of heart attack compared with women who had normal thyroid hormone levels. Subclinical hypothyroidism is relatively common, affecting an estimated 17% of older Americans.
Importantly, these associations remained significant even after adjusting for other major cardiovascular risk factors, including body weight, smoking status, cholesterol levels, and blood pressure. Women with autoimmune forms of hypothyroidism were found to have an even greater increase in risk.
The researchers concluded that subclinical hypothyroidism is a strong marker for increased risk of atherosclerosis and myocardial infarction in elderly women, highlighting the cardiovascular significance of even mild thyroid dysfunction.
For a broader overview of thyroid symptoms, testing, and thyroid disorders, see Thyroid Health: Symptoms, Testing, and Common Thyroid Disorders. You can also check out this article: Hidden Hypothyroidism: Symptoms, Testing, and Why It Is Often Missed
