What is a thyroid peroxidase (TPO) antibody test?

What does the TPO antibody test measure?

Thyroid antibodies are autoantibodies: proteins the immune system makes by mistake that can affect the thyroid’s ability to make hormones. MedlinePlus

Thyroid peroxidase antibodies (TPOAb) are one type. High levels are a sign that Hashimoto disease or Graves disease may be involved. MedlinePlus

Why is the TPO antibody test ordered?

• When TSH, T4 or T3 results are too high or too low, to see whether an autoimmune disease is causing the problem. MedlinePlus
• To screen people at higher risk of autoimmune thyroid disease, such as those with a family history or another autoimmune condition. MedlinePlus

What are typical TPO antibody ranges?

ARUP Laboratories publishes a single reference interval for its TPO antibody test. ARUP Laboratories

Reference ranges differ between laboratories and testing methods, and many also differ by age, sex, pregnancy or the phase of the menstrual cycle. The range printed on your own report is the one that applies to your result, and a clinician interprets it alongside your history.

What can affect TPO antibody results?

• Biotin, often found in hair, skin and nail supplements, can interfere with some lab tests and cause incorrect results. Tell the person ordering the test if you take it. FDA
• Ask the person ordering the test whether you need to fast, stop any supplement, or schedule the draw at a particular time.

When should you talk to a clinician about a TPO antibody result?

• Your provider decides which antibody tests to use based on symptoms, other results and your medical and family history. MedlinePlus

DiscoverMedica explains what a test measures and what named sources publish. It does not interpret individual results; the clinician who ordered your test, or one you choose, does.

Where can you get a TPO antibody test?

A clinician can order it as part of routine or follow-up care. Some services also let you order lab tests yourself; check that a service’s panel includes this marker, which laboratory runs it, and who reviews the result with you.

• Function HealthAnnual membership for broad lab panels, drawn at Quest sites or at home.
• Quest HealthOrder individual lab tests from Quest Diagnostics online, without a doctor’s visit.

TPO Antibody Test: questions, answered

Sources

1. MedlinePlus: Thyroid Antibodies
2. ARUP Laboratories: Thyroid Peroxidase (TPO) Antibody (test 0050075)
3. FDA: Biotin Interference with Lab Tests

Last reviewed October 7, 2026. Every source above was checked on or before that date. Educational information only, not medical advice; it does not replace a conversation with a licensed clinician. DiscoverMedica does not employ clinicians.