Thyrotropin; Thyroid stimulating hormone; Hypothyroidism - TSH; Hyperthyroidism - TSH; Goiter - TSH
A TSH test measures the amount of thyroid stimulating hormone (TSH) in your blood. TSH is produced by the pituitary gland. It prompts the thyroid gland to make and release thyroid hormones into the blood.
A blood sample is needed. Other thyroid tests that may be done at the same time include:
There is no preparation needed for this test. Ask your health care provider about any medicines you are taking that may affect the test results. DO NOT stop taking any medicines without first asking your provider.
Medicines you may need to stop for a short time include:
The vitamin biotin (B7) can affect the results of the TSH test. If you take biotin, talk to your provider before you have any thyroid function tests.
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Your provider may also check your TSH level if you are planning to get pregnant.
Normal values range from 0.5 to 5 microunits per milliliter (µU/mL).
TSH values can vary during the day. It is best to have the test early in the morning. Experts do not fully agree on what the upper number should be when diagnosing thyroid disorders.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
If you are being treated for a thyroid disorder, your TSH level will likely be kept between 0.5 and 4.0 µU/mL, except when:
A higher-than-normal TSH level is most often due to an underactive thyroid gland (hypothyroidism). There are many causes of this problem.
A lower-than-normal level may be due to an overactive thyroid gland, which can be caused by:
Use of certain medicines may also cause a lower-than-normal TSH level. These include glucocorticoids/steroids, dopamine, certain chemotherapy drugs, and opioid painkillers such as morphine.
There is little risk involved with having your blood taken.Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
Guber HA, Farag AF. Evaluation of endocrine function. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 24.
Jonklaas J, Cooper DS. Thyroid. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 213.
Salvatore D, Cohen R, Kopp PA, Larsen PR. Thyroid pathophysiology and diagnostic evaluation. In: Melmed S, Auchus RJ, Goldfine AB, Koenig RJ, Rosen CJ, eds. Williams Textbook of Endocrinology. 14th ed. Philadelphia, PA: Elsevier; 2020:chap 11.
Weiss RE, Refetoff S. Thyroid function testing. In: Jameson JL, De Groot LJ, de Kretser DM, et al, eds. Endocrinology: Adult and Pediatric. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 78.BACK TO TOP
Review Date: 1/26/2020
Reviewed By: Brent Wisse, MD, board certified in Metabolism/Endocrinology, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2020 A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.