At a Glance
Why Get Tested?
When to Get Tested?
Prior to and after the completion of treatment for thyroid cancer, before and after radioactive iodine therapy, and at regular intervals to monitor for recurrence
A blood sample drawn from a vein in your arm
Test Preparation Needed?
The Test Sample
What is being tested?
This test measures the amount of thyroglobulin in the blood. Thyroglobulin is a protein produced by the thyroid gland. The thyroid gland helps to regulate the rate at which the body uses energy. It is a small butterfly-shaped organ that lies flat against the windpipe in the throat and is composed primarily of very small, ball-shaped structures called follicles. Cells in the follicles produce and store thyroglobulin, breaking it down as needed into the thyroid hormones T4 (thyroxine) and T3 (triiodothyronine). The production of these hormones and their release into the blood stream is stimulated by the pituitary hormone TSH (thyroid stimulating hormone). No other part of the body makes thyroglobulin, but it is produced by many thyroid cancers, both those confined to the thyroid gland and those that have spread to other parts of the body.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
Ask a Laboratory Scientist
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 916-918.
Clarke, W. and Dufour, D. R., Editors (© 2006). Contemporary Practice in Clinical Chemistry: AACC Press, Washington, DC. Pp 372.
Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 1030-1031.
(Revised 2009 May 14). How Is Thyroid Cancer Diagnosed? American Cancer Society [On-line information]. Available online at http://www.cancer.org/docroot/cri/content/cri_2_4_3x_how_is_thyroid_cancer_diagnosed_43.asp?sitearea=&level= through http://www.cancer.org. Accessed October 2009.
Grebe, S. (2009 March 25). Diagnosis and Management of Thyroid Carcinoma: A Focus on Serum Thyroglobulin. Medscape Today from Expert Review of Endocrinology and Metabolism [On-line information]. Available online at http://www.medscape.com/viewarticle/586810 through http://www.medscape.com. Accessed October 2009.
Hershman, J. (Reviewed 2008 June). Thyroid Disorders, Introduction. Merck Manual for Healthcare Professionals [On-line information]. Available online at http://www.merck.com/mmpe/sec12/ch152/ch152a.html?qt=thyroglobulin&alt=sh through http://www.merck.com. Accessed October 2009.
Hoofnagle, A. and Wener, M. H. (2006 December). Serum thyroglobulin: a model of immunoassay imperfection. Clinical Laboratory International, CLI-Online.com v8 [On-line information]. PDF available for download at http://www.cli-online.com/fileadmin/artimg/serum-thyroglobulin-a-model-of-immunoassay-imperfection.pdf through http://www.cli-online.com. Accessed October 2009.
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.
Schlumberger, M. and Baudin, E. (1998). Serum Thyroglobulin determination in the follow-up of patients with differentiated thyroid carcinoma. European Journal of Endocrinology [On-line journal], vol (138) Pp 249-252. PDF available for download at http://www.eje.org/eje/138/0249/1380249.pdf through http://www.eje.org.
What is Thyroglobulin? John Hopkins Thyroid Tumor Center [On-line information]. Available online through http://www.thyroid-cancer.net.
Spencer, C. Thyroglobulin (Tg) and Tg Antibody (TgAb) Testing for Patients Treated for Thyroid Cancers. Thyroid Cancer Survivors' Association, Inc. [On-line article]. Available online at http://www.thyca.org/thyroglobulin.htm through http://www.thyca.org.
ARUP. Thyroglobulin and Thyroglobulin Antibody. ARUP lab [On-line testing information]. Available online at http://www.aruplab.com/guides/clt/tests/clt_215b.htm through http://www.aruplab.com.
ACS (2001 July 5). All About Thyroid Cancer, Detailed Guide. American Cancer Society [On-line information]. Available online at http://www.cancer.org/eprise/main/docroot/cri/cri_2_3x?dt=43 through http://www.cancer.org.
MEDLINEplus (2001 November 23). Antithyroglobulin antibody. MEDLINEplus [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003557.htm through http://www.nlm.nih.gov.
ATA (2002). Cancer of the Thyroid. The American Thyroid Association [On-line information]. Available online at http://www.thyroid.org/resources/patients/brochures/thyroid_cancer.html through http://www.thyroid.org.
(© 2005). Cancer of the Thyroid. American Thyroid Association [On-line information]. PDF available for download at http://www.thyroid.org/patients/brochures/ThyroidCancer_brochure.pdf through http://www.thyroid.org.
Whitley, RJ and Ain, KB (2004). Thyroglobulin: a specific serum marker for the management of thyroid carcinoma. Medscape from Clin Lab Med. 2004; 24(1):29-47 (ISSN: 0272-2712) [On-line Abstract] Available online at http://www.medscape.com/medline/abstract/15157556?queryText=thyroglobulin through http://www.medscape.com.
Liebert, M.A. (2003 June 05). Thyroid Tests for the Clinical Biochemist and Physician Thyroglobulin (Tg) Measurement. Medscape from Thyroid 13(1):57-67, 2003. [On-line information]. Available online at http://www.medscape.com/viewarticle/452669_print through http://www.medscape.com.
(© 2006). Thyroglobulin and Thyroglobulin Antibody. ARUP's Guide to Clinical Laboratory Testing [On-line information]. Available online at http://www.arup-lab.com/guides/clt/tests/clt_249b.jsp#1149079 through http://www.arup-lab.com.