This test is vital to detect thyroid disorders and monitor the patient during the treatment of the hypo or hyperthyroidism. It measures the level of Thyroid Simulating Hormone (TSH) in the blood. The pituitary gland, which is attached to the base of the brain, secrets TSH. In addition it functions by stimulating the thyroid gland to secrete its hormones. The thyroid gland, located beneath the larynx, is the internal thermostat of the body that regulates temperature by secreting T4- Thyroxine and T3- Triiodothyronine hormones. These hormones control the speed of energy utilization. Testing for the levels of thyroid hormone T4 is recommended with this test.