What Is Thyroid Peroxidase (TPO) Antibody?

Anti-TPO antibodies attack thyroid peroxidase, an enzyme needed for thyroid hormone production.

What It Means

• Positive in 90–95% of Hashimoto's patients
• Also in 10–15% of healthy people (especially women)
• Higher levels = faster progression to hypothyroidism

When Ordered

• Elevated TSH
• Family history
• Other autoimmune conditions
• Pregnancy (risk of postpartum thyroiditis)

Important

• Positive antibodies confirm autoimmune cause but don't require treatment by themselves
• Treatment based on TSH and free T4