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Thyroperoxidase Antibody Levels Blood Test

Last updated May 10, 2019

Approved by: Maulik P. Purohit MD, MPH

The Thyroperoxidase Antibody Levels Blood Test detects thyroperoxidase autoantibodies in blood. It is used to diagnose autoimmune disorders of the thyroid.

What are the other Names for this Test? (Equivalent Terms)

  • Anti-TPO Levels Blood Test
  • Thyroperoxidase Antibody Levels Blood Test
  • TPO Antibody Levels Blood Test

What is the Thyroperoxidase Antibody Levels Blood Test? (Background Information)

  • Thyroperoxidase (or thyroid peroxidase, TPO) is an enzyme needed for the production of thyroid hormones. The presence of autoantibodies to TPO may signal an autoimmune thyroid disorder
  • The thyroid gland is situated in the front of the throat, just below the cartilage of the Adam’s apple. It produces 3 main hormones that affect nearly every cell in the body:

    • Two thyroid gland hormones, thyroxine (T4) and triiodothyronine (T3), ramp up the metabolism. They increase the consumption of energy and oxygen and they also stimulate growth and development
    • The third hormone produced by the thyroid gland is calcitonin, made by C cells. It decreases calcium levels in blood, by stimulating calcium excretion by the kidneys and calcium uptake by the bones       
  • Thyroperoxidase is an enzyme in the thyroid gland that uses iodine to make T4 and T3. Without iodine, the production of these hormones stops. This can lead to the formation of a goiter in the neck as levels of fluid and hormone precursors accumulate
  • Problems with thyroperoxidase may also impair thyroid hormone production. An example of this is the mistaken targeting of thyroperoxidase by antibodies of the immune system. This leads to tissue destruction and impaired thyroid function
  • Antibodies are bodily defense proteins that recognize foreign invaders, such as bacteria. They interact with the immune system and initiate an immune response to rid the body of the invader
  • Autoantibodies are antibodies that mistakenly recognize the body’s own cells as foreign invaders. The presence in blood of autoantibodies to thyroperoxidase point to an autoimmune disorder of the thyroid
  • The Thyroperoxidase Antibody Levels Blood Test detects thyroperoxidase autoantibodies in blood. It is used to diagnose autoimmune disorders of the thyroid

What are the Clinical Indications for performing the Thyroperoxidase Antibody Levels Blood Test?

Following are the clinical indications for performing the Thyroperoxidase Antibody Levels Blood Test:

  • Following up to a thyroid panel blood test
  • Rapid weight change
  • Goiter
  • Protruding eyes (exophthalmos)
  • Anxiety
  • Tremors
  • Hair loss
  • Menstrual irregularity, diminished menstrual cycle
  • Abnormal uterine bleeding
  • Early or late onset of puberty
  • Masculinization in females, such as excessive hair growth
  • Infertility, erectile dysfunction
  • Decreased sex drive
  • Rapid heart rate
  • Fatigue

How is the Specimen Collected for Thyroperoxidase Antibody Levels Blood Test?

Following is the specimen collection process for Thyroperoxidase Antibody Levels Blood Test:

Sample required: Blood

Process of obtaining blood sample in adults:

  • A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
  • The site is cleaned with 70% alcohol in an outward spiral, away from the zone of needle insertion
  • The needle cap is removed and is held in line with the vein, pulling the skin tight
  • With a small and quick thrust, the vein is penetrated using the needle
  • The required amount of blood sample is collected by pulling the plunger of the syringe out slowly
  • The wrap band is removed, gauze is placed on the collection site, and the needle is removed
  • The blood is immediately transferred into the blood container, which has the appropriate preservative/clot activator/anti-coagulant
  • The syringe and the needle are disposed into the appropriate “sharp container” for safe and hygienic disposal

Preparation required: No special preparation is needed prior to the test.

What is the Significance of the Thyroperoxidase Antibody Levels Blood Test Result?

A positive Thyroperoxidase Antibody Levels Blood Test may indicate:

  • Hashimoto thyroiditis
  • Graves’ disease

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • Similar tests that investigate suspected thyroid autoimmune diseases include thyroglobulin antibody, thyroid stimulating hormone receptor antibody, and thyroid stimulating immunoglobulin tests

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

  • The thyroid autoantibodies test is a blood test to detect thyroid autoantibodies. It is used to diagnose autoimmune thyroid disease

The following article link will help you understand the thyroid autoantibodies test:


Please visit our Laboratory Procedures Center for more physician-approved health information:


References and Information Sources used for the Article:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Sept. 13, 2015
Last updated: May 10, 2019