What is thyroglobulin?

Thyroglobulin (Tg) is a protein made by the thyroid that carries thyroid hormone. The thyroid gland is the only organ which makes Tg. Therefore, Tg is a good test to tell if there are thyroid cells in the body. Once the whole thyroid is taken out, the thyroglobulin level should go down to close to zero. Thyroglobulin levels can then be measured, by a simple blood test, after thyroidectomy. Thyroglobulin is used as a tumor marker (test to see how much cancer is in the body) for thyroid cancer. If thyroglobulin levels go up after removing the whole thyroid, there is concern that the cancer may have come back (recurred) or spread (metastasized).

Thyroglobulin is a protein produced by the thyroid gland. It is used to make the thyroid hormones thyroxine (T4) and triiodothyronine (T3).

Thyroglobulin levels may be elevated if thyroid cancer is present. Elevated levels after thyroid surgery may also indicate metastatic or recurrent thyroid cancer.