Guide. Thyroid hormone tests are blood tests that check how well the thyroid gland is working. The thyroid gland makes hormones that regulate the way the body uses energy. The thyroid gland is a butterfly-shaped gland that lies in front of your windpipe (trachea), just below your voice box (larynx).hyroid hormone tests are done to: 1  Find out what is causing an abnormal thyroid-stimulating hormone (TSH) test. 2  For more information, see the topic Thyroid-Stimulating Hormone (TSH) . 3  This is the most common reason for thyroid hormone tests. 4  Check how well treatment of thyroid disease is working.