In patients with autoimmune thyroid disease (AITD), multiple autoantibodies against thyroid antigens can be detected in the serum. Thyroperoxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb) are commonly used in the diagnosis of autoimmune thyroid diseases. In clinical practice, TPOAb plays a crucial role in the early screening of autoimmune diseases and serves as the preferred marker for the diagnosis of Graves' disease (GD), also known as diffuse toxic goiter, and Hashimoto's thyroiditis. In the development of TPOAb diagnostic kits, TPO is the key diagnostic component.

Thyroperoxidase (TPO) is a transmembrane glycoprotein with a molecular weight of approximately 103 kDa. It is a heme-containing enzyme located in the apical membrane of thyroid follicular cells, where it catalyzes two essential reactions for thyroid hormone synthesis: the iodination of tyrosyl residues in thyroglobulin and the oxidative coupling that produces thyroxine and triiodothyronine.