The thyroid gland, one of the endocrine glands, is a butterfly-shaped gland located in the frontal portion of the neck. The hormones secreted by the gland regulate growth, metabolism, sexual development, and many other important functions of our body. Thyroxine, triiodothyronine and calcitonin are the three hormones secreted by the thyroid gland. These hormones travel through the blood and reach the body cells. Oversecretion or undersecretion of these hormones leads to thyroid diseases.