Anti-TPO (Anti-Thyroid Peroxidase) Antibody Test

The Anti-TPO test detects antibodies your immune system has mistakenly produced against thyroid peroxidase, an enzyme that plays a key role in the thyroid gland's production of hormones.

The presence of these antibodies is a hallmark of autoimmune thyroid disease, where the body's own immune system attacks the thyroid gland, gradually impairing its ability to function normally over months or years.

This test is particularly valuable because Anti-TPO antibodies can be detectable years before a person develops overt symptoms or abnormal TSH levels, making it a useful early marker for people at risk of future thyroid dysfunction.

It's most commonly used to confirm Hashimoto's thyroiditis, the leading cause of hypothyroidism in many parts of the world, and to help distinguish autoimmune thyroid disease from other, non-autoimmune causes of thyroid dysfunction.