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Latest Edit: Hector 2014-03-21 (EDT)

See Also Lab Tests

This test is used as a primary tumor marker for well-differentiated thyroid cancer. [1]


  • 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).

Patient Preparation

  • 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

Clinical Implications

High levels indicate:

  • Residula thyroid tissue in the neck
  • Metastatic thyroid cancer

Associated Tests

  • Antithyroglobulin antibody


  1. Pagana Kathleen D, Pagana Timothy J (2006) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby.