The thyroid gland produces two main hormones, Thyroxine and Tri-iodothyronine (T-3). These hormones circulate in the bloodstream and help regulate metabolism. They maintain the rate at which the body uses fats and carbohydrates, helps control the body’s temperature, influences heart rate, and helps regulate the production of proteins. The thyroid gland also produces calcitonin, which is a hormone that helps regulate the amount of calcium in the blood.
The pituitary gland and hypothalamus controls the rate at which these hormones are produced and released. The process begins when the hypothalamus signals the pituitary gland to make a hormone known as thyroid-stimulating hormone (TSH). The pituitary gland releases a certain amount of TSH, depending on how much thyroxine and T-3 are in the blood. The thyroid gland, in turn, regulates its production of hormones based on the amount of TSH it receives from the pituitary gland.