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Also known as: Tg
Formal name: Thyroglobulin, Serum or Plasma

The Test Sample

What is being tested?

Thyroglobulin is a protein produced by the thyroid gland. This test measures the amount of thyroglobulin in the blood.

Location of the thyroid

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 that produce and store thyroglobulin (Tg). Thyroglobulin then breaks down as needed into the thyroid hormones T4 (thyroxine) and T3 (triiodothyronine). The production of these hormones and their release into the bloodstream are stimulated by the pituitary hormone TSH (thyroid stimulating hormone).

Thyroglobulin is not produced by every thyroid cancer, but the most common types, the well-differentiated papillary and follicular thyroid cancers, frequently do, resulting in increased levels of thyroglobulin in the blood.

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.