At a Glance
Why Get Tested?
To monitor treatment of some types of thyroid cancer and to detect recurrence
When to Get Tested?
Once treatment for thyroid cancer has been completed, before and after radioactive iodine therapy for thyroid cancer, and at regular intervals to monitor for recurrence
A blood sample taken from a vein in your arm
The Test Sample
What is being tested?
This test measures the amount of thyroglobulin in the blood. Thyroglobulin is a protein produced by follicle cells in the thyroid gland. The thyroid gland is a small butterfly shaped organ that helps to regulate the rate at which the body uses energy. The thyroid lies flat against the windpipe in the throat and is composed primarily of very small, ball-shaped structures called follicles. Cells inside the follicles produce and store thyroglobulin, breaking it down when needed into the thyroid hormones T4 (thyroxine) and T3 (triidothyronine). 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.
Ask a Laboratory Scientist
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.