Anti-TPO antibodies

Antibodies directed against thyroperoxidase (TPO), a key enzyme in thyroid hormone synthesis. Their presence in blood is the main biological marker of Hashimoto's thyroiditis. Elevated anti-TPO levels signal an autoimmune attack against the thyroid, even without symptoms or thyroid hormone abnormalities. Testing is recommended in the evaluation of hypothyroidism, unexplained fatigue or family history of autoimmune thyroid disease.