Thyroid Peroxidase

Thyroid peroxidase (TPO) is a transmembrane protein of 107kDa containing a heme prosthetic group. It is present as a dimer on the apical surface of thyroid follicular cells. TPO is the primary enzyme involved in thyroid hormone synthesis. Malignant thyroid tumors exhibit an anomaly in TPO resulting in lower affinity for anti-TPO. This antibody may aid in the differentiation between benign and malignant thyroid tumors.