Thyroid-stimulating hormone (TSH) is secreted by the pituitary gland, located at the base of the brain. A laboratory test that measures the level of TSH in the blood screens for, helps diagnose and monitors treatment of thyroid disorders.
TSH regulates the amounts of thyroid hormones (T3 and T4) released by the thyroid gland into the blood. Thyroid hormones help control the body's metabolism.
Individuals showing an enlarged thyroid gland in the neck, or symptoms of low or high metabolism get tested for TSH. TSH tests are also used to monitor thyroid disease treatment.
TSH testing uses a blood sample collected from an arm vein or infant's heel.
A high TSH result indicates hypothyroidism—low metabolism. A low TSH level indicates hyperthyroidism—high metabolism.
An abnormal TSH result indicates an excess or deficiency of the thyroid-stimulating hormone in the blood, but it doesn't necessarily reveal the cause for such levels without additional tests.