A patient seated in the chair before a blood draw
In person

Thyroid Peroxidase (TPO) Antibody

Antibodies against a thyroid enzyme, measured from one blood draw.

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  • 2,000+ lab locations. Find one near you
  • Nothing due at the lab. FSA / HSA accepted
  • Ordered by a licensed clinician

At a glance

Collection
Blood draw
A standard blood draw at the lab.
Preparation
None
Nothing to do ahead of time. Water is fine.
Results
1 to 3 days
Typical turnaround after your visit.
Where
2,000+ lab locations
Nationwide, with nothing due at the lab.

About this test

Thyroid peroxidase (TPO) is an enzyme the thyroid uses to make its hormones. This test measures antibodies against it, which relate to autoimmune thyroid conditions. People check it with a family history or a borderline TSH, and a positive result alone is not a diagnosis. No fasting needed.

For adults 18 and older. Test availability varies by lab location.

Who should take this test?

Often checked with a family history of thyroid conditions or a borderline TSH, this test is for adults with questions about autoimmune thyroid conditions.

Ask about this test

Not sure this is the right test?

AI-generated. For information only, not medical advice. Call 911 for an emergency.

What does this test measure?

Your result shows whether TPO antibodies are above the lab’s reference range, which a healthcare provider reads with TSH and thyroid hormone levels to understand your thyroid.

Thyroid peroxidase (TPO) antibodies
TPO is an enzyme your thyroid uses to make hormone. TPO antibodies are made when the immune system targets the thyroid. They are often found in autoimmune thyroid conditions, but some people have them without thyroid problems, so a positive result is read with TSH and thyroid hormones.
Why it’s measured: Antibodies often found in autoimmune thyroid conditions, read with TSH and thyroid hormones.

How it works

  1. Step 1

    Order online

    Check out here. A licensed clinician in your state reviews your order and sends it to the lab.

  2. Step 2

    Visit a lab

    Bring a photo ID to any of 2,000+ lab locations. No fasting needed, and nothing is due at the lab.

  3. Step 3

    Get your results

    Results post to your account, usually in 1 to 3 days, each number next to the lab’s reference range.

Find a lab near you

Choose from 2,000+ lab locations nationwide. Your order works at any of them.

What your results tell you

TPO antibodies are reported in international units per milliliter (IU/mL) and compared with the lab’s reference range.

  • Your number next to the lab’s reference range
  • Explained in plain language
  • A licensed clinician reviews your order and, if appropriate, orders the test.
  • A lab report you can download and share

A positive result is a reason to talk with a healthcare provider, who reads it with your TSH and thyroid hormone levels.

TPO or thyroglobulin antibodies?

Two thyroid antibodies that are often read together.

TPO antibody

Antibodies to thyroid peroxidase, an enzyme used to make thyroid hormone.

Targets
Thyroid peroxidase, an enzyme in the thyroid
Related to
Autoimmune thyroid conditions
Read with
TSH and thyroid hormone levels

Clinical-grade testing, from the comfort of home.

From the lab to your report, every step of our process meets the gold standard in medical testing.

  • CLIA-certified labs

    Every lab we partner with is certified under the Clinical Laboratory Improvement Amendments, meeting both state and federal standards with regular independent inspections.

  • We protect your health data

    We protect your health data with encryption and do not sell it. Some results must be reported to public health authorities by law. See our Privacy Notice.

  • Rigorous quality assurance

    All partner labs run regular internal quality checks, participate in proficiency testing, and comply with federal and state lab regulations.

  • Clinician-reviewed reports

    Results are reviewed by an independent, licensed clinician.

Questions

Common questions.

Anything else, our care team answers by phone, text, or email.

TPO is an enzyme in the thyroid that helps make thyroid hormone. In autoimmune thyroid conditions, the immune system can make antibodies against it.

Alongside other tests, TPO antibodies can aid in evaluating thyroid conditions such as Hashimoto’s thyroiditis and Graves’ disease.

Yes. Antibodies can be present while TSH and thyroid hormone levels are within range. That is why a positive result on its own is not a diagnosis. A healthcare provider may suggest checking your thyroid levels over time, depending on your results and history.

They are often checked when TSH is raised or borderline, or when thyroid conditions run in the family. Alongside Free T4, TPO antibody testing can help a healthcare provider understand a raised TSH. A healthcare provider can explain whether it fits your situation.

Lab tests are informational and don’t diagnose conditions on their own. Available to adults 18 and older; test availability varies by lab location. A licensed clinician reviews your order and, if appropriate, orders the test. All testing is performed at CLIA-certified laboratories. Not for emergencies: if you think you may be having a medical emergency, call 911.