From Health Facts
Latest Edit: Hector 2014-03-21 (EDT)
This test is used as a primary tumor marker for well-differentiated thyroid cancer. 
- Thyroglobulin or Tg, is the protein precursor of thyroid hormone. It is made by normal well-differentiated benign thyroid cells or thyroid cancer cells.
- Since Tg is only made by thyroid cells, it allows for the detection of the presence or absence of thyroid cells, particularly after thyroid cancer surgery.
- Tg is also used as a tumor marker in postoperative patients, as it is a marker of disease activity and the volume of thyroid tumor. Ideally, Tg levels will be low or undetectable after treatment (usualyl surgery followed by radioactive iodine).
- No fasting required.
- Factors which can cause increased levels
- Thyroglobulin autoantibodies
- Factors which can cause decreased levels
- Less well-differentiated thyroid cancers, patients whose tumors do not have TSH receptors or whose tumors cannot make Tg, thyroglobulin autoantibodies
High levels indicate:
- Residula thyroid tissue in the neck
- Metastatic thyroid cancer
- Antithyroglobulin antibody
- Pagana Kathleen D, Pagana Timothy J (2006) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby.