Anti TPO test is often used to assist clinicians in the definitive diagnosis of autoimmune thyroiditis, differential diagnosis of thyroid disease due to autoimmune causes or other causes, as well as help clinicians make treatment decisions for patients with subclinical hypothyroidism.

Anti TPO (Thyroid Antibody) is also known as Thyroid Peroxidase Antibody (TPO-Ab) - an antibody against the enzyme Thyroid Peroxidase. Thyroid peroxidase is an enzyme involved in the synthesis of thyroid hormones, helping to attach iodine molecules to the protein frame thyroglobulin. When the body produces autoantibodies that attack this enzyme, it will reduce or stop the above process.