Thyroid peroxidase or Thyroperoxidase (TPO) is an enzyme mainly expressed in the thyroid that liberates iodine for addition onto tyrosine residues on thyroglobulin for the production of thyroxine (T4) or triiodothyronine (T3) (thyroid hormones). This process is termed the "organification of iodine".

It is inhibited by the thioamide drugs, such as propylthiouracil. It is a frequent epitope of autoantibodies in autoimmune thyroid disease.

External link

EC 1.11.1