THYROID PEROXIDASE and THYROGLOBULIN ANTIBODIES

Thyroid Peroxidase and Thyroglobulin Antibodies

Thyroid peroxidase (TPO) is a glycosylated heme-protein located in the apical membrane of the thyrocyte, where it catalyzes iodide oxidation and further incorporation in the thyroglobulin molecule. TPO shares sequence homology with lactoperoxidase, myeloperoxidase and eosinophil peroxidase.  Autoantibodies to thyroid peroxidase (TPOAb) are produced within the body. The presence of TPOAb in the blood reflects a prior attack on the thyroid tissue by the body's immune system.

The presence of TPO antibodies in your blood suggests that the cause of thyroid disease is an autoimmune disorder, such as Hashimoto's disease or Graves' disease. In autoimmune disorders, your immune system makes antibodies that mistakenly attack normal tissue.

Thyroglobulin (Tg) is a protein produced uniquely by your thyroid gland. This test measures the amount of thyroglobulin in the blood. The thyroid gland produces hormones (thyroxine or T4 and triiodothyronine or T3) that help to regulate the rate at which the body uses energy. It is a small, butterfly-shaped organ that lies flat against the windpipe at the base of the throat and is composed primarily of very small, ball-shaped structures called follicles that produce and store thyroglobulin.

Antithyroglobulin antibodies can be a sign of thyroid gland damage caused by the immune system. They may be measured if thyroiditis is suspected.

A thyroglobulin antibodies (TgAb) test is used to check blood levels of antibodies the body has made against the compound thyroglobulin.