Low thyroid function may put women at risk of a heart attack. A study published in the Archives of Internal Medicine evaluated over 17,000 women with no signs of heart disease. Those with low thyroid hormone levels but no physical signs of thyroid disease were at a 69 percent higher risk of a heart attack, possibly due to a rise in blood pressure and abnormal cholesterol levels.

Similar findings were not noted in men.

It is not clear if treatment with synthetic thyroid hormone could prevent heart disease. More studies need to be done to better understand the connection between thyroid levels and heart disease.