If you have some form of heart disease and your condition worsens, be sure that your thyroid function is checked regularly, as it may be contributing to your problems. The thyroids function is to absorb iodine, an element found mainly in salt, bread, and fish, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3). These hormones control the bodys metabolism, which controls the function of your heart, brain, skin, and digestive system. This means that if your thyroid isnt doing its job properly it can affect almost every aspect of your health. "Thyroid hormone is very important for normal cardiovascular function, such as normal blood pumping function of the heart, normal heart rate, regulating normal blood pressure control, and regulating blood cholesterol levels," says Betul A. Hatipoglu, a staff member in the Department of Endocrinology, Diabetes and Metabolism at Cleveland Clinic.