Also known as MA (thyroid peroxidase antibody, microsomal antibody), TPO is an antibody against thyroid peroxidase. Thyroid peroxidase is an enzyme that plays an important role in the chemical reactions that produce the thyroid hormones. TPO blocks thyroid peroxidase and in that way impairs thyroid hormone production. With Hashimoto type autoimmune thyroiditis, TPO antibodies are high in 90% of cases.
TgAB (thyroglobulin antibody) is directed against thyroglobulin. Thyroglobulin is the precursor and storage form of the thyroid hormones T3 and T4. With thyroid cancer and after removal of the thyroid gland, TgAB serves as a tumor marker. An elevated TgAb titer with an intact thyroid gland is an indicator of a thyroid disease, however it is not typical of any specific disease.
(TSH receptor antibody) is directed against the TSH docking sites on the thyroid gland cells (TSH receptors). TRAb binding in the thyroid gland simulates TSH binding and leads to increased release of thyroid hormones. Elevated TRAb titer in blood is typical of Grave’s disease.