They help generate heart rate, blood pressure, body temperature and the rate at which food is converted into energy. The 2 main thyroid hormones are T3 (triiodothyronine) and T4 (thyroxine). The amount of thyroid hormone secreted is controlled by another hormone, called thyroid-stimulating hormone (TSH), which is released by the pituitary gland in your head ("How Your Thyroid Works"). Thyroid hormones act throughout the body, influencing metabolism, growth and development, and body temperature. During infancy and childhood, adequate thyroid hormone levels are crucial for brain development (Tree, 2013). The thyroid gland also produces the hormone calcitonin, which is involved in calcium metabolism and stimulates bone cells to add calcium to bones (“How Your Thyroid Works")