Thyroid peroxidase antibody test: What is it?

What is a thyroid peroxidase antibody test? Does it diagnose thyroid disease?

Answer From Todd B. Nippoldt, M.D.

Thyroid peroxidase (TPO) is an enzyme normally found in the thyroid gland. TPO plays an important role in the production of thyroid hormones. A TPO test detects antibodies against TPO in the blood. If you’ve been diagnosed with thyroid disease, your doctor may suggest a TPO antibody test and other thyroid tests to help find the cause.

The presence of TPO antibodies in your blood suggests that the cause of thyroid disease is an autoimmune disorder, such as Hashimoto’s disease or Graves’ disease. In autoimmune disorders, your immune system makes antibodies that mistakenly attack normal tissue. Antibodies that attack the thyroid gland cause swelling, rarely tenderness and reduced function of the thyroid.

Your doctor may also order a TPO antibody test if you are pregnant and have an autoimmune disease that involves the thyroid, such as Hashimoto’s disease or Graves’ disease.

Some people with TPO antibodies may not have thyroid disease. But the presence of TPO antibodies may increase the risk of future thyroid disorders.

There is a problem with
information submitted for this request. Review/update the
information highlighted below and resubmit the form.

From Mayo Clinic to your inbox

Sign up for free, and stay up to date on research advancements, health tips and current health topics, like COVID-19, plus expertise on managing health. Click here for an email preview.

Email

ErrorEmail field is required

ErrorInclude a valid email address

To provide you with the most relevant and helpful information, and understand which
information is beneficial, we may combine your email and website usage information with
other information we have about you. If you are a Mayo Clinic patient, this could
include protected health information. If we combine this information with your protected
health information, we will treat all of that information as protected health
information and will only use or disclose that information as set forth in our notice of
privacy practices. You may opt-out of email communications at any time by clicking on
the unsubscribe link in the e-mail.

Thank you for subscribing!

You’ll soon start receiving the latest Mayo Clinic health information you requested in your inbox.

Sorry something went wrong with your subscription

Please, try again in a couple of minutes

1. Thyroid function tests. American Thyroid Association. https://www.thyroid.org/thyroid-function-tests/. Accessed Aug. 5, 2020.
2. Overview of thyroid function. Merck Manual Professional Version. https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/thyroid-disorders/overview-of-thyroid-function?query=overview thyroid function. Accessed Aug. 5, 2020.
3. Postpartum thyroiditis. American Thyroid Association. http://www.thyroid.org/postpartum-thyroiditis/. Accessed Aug. 5, 2020.
4. Jameson JL, et al., eds. Thyroid gland physiology and testing. In: Harrison’s Principles of Internal Medicine. 20th ed. The McGraw-Hill Companies; 2018. https://accessmedicine.mhmedical.com. Accessed Aug. 5, 2020.
5. Laposata M. The endocrine system. In: Laposata’s Laboratory Medicine: Diagnosis of Disease in the Clinical Laboratory. 3rd ed. The McGraw-Hill Companies; 2019. https://accessmedicine.mhmedical.com. Accessed Aug. 5, 2020.
6. AskMayoExpert. Thyroid tests. Mayo Clinic; 2020.

See more Expert Answers