1. Uptake of iodide(I-) by follicular cell
2. oxidation of iodide to produce molecular iodine
3. Organification
   1. iodination of tyrosine residues on thyroglobulin
   2. MIT and DIT
4. Coupling - formation of T4 and T3
5. Proteolysis of thyroglobulin and secretion of thyroid hormones
6. Conversion of T4 to T3

Thyroid peroxidase is a multifunctional enzyme responsible for

• catalyzing the oxidation of iodide,
• the iodination of thyroglobulin, and
• the coupling reaction between 2 iodized tyrosine residues.

Antibodies against thyroid peroxidase are present in >90% of patients with autoimmune (Hashimoto's) thyroiditis.