Thyroid Peroxidase Antibodies (TPO)

The Thyroid Peroxidase Antibodies (TPO) test contains 1 test with 1 biomarker.

Description: Thyroid Peroxidase is a blood test used to check for thyroid autoimmune disorders.

Also Known As: Thyroid Autoantibodies Test, Antithyroid Antibodies Test, Thyroid Peroxidase Antibody Test, Thyroperoxidase Antibody Test, TPO Test, Anti-TPO Test

Collection Method: Blood Draw

Specimen Type: Serum

Test Preparation: No preparation required

When is a Thyroid Peroxidase test ordered?

When a person has irregular TSH and/or free T4 test results, symptoms of low or high thyroid hormone levels, or the appearance of a goiter, testing may be performed, especially if the reason is considered to be an autoimmune condition.

Hypothyroidism can produce a variety of symptoms, including:

  • Gaining weight
  • Fatigue
  • Skin that is dry
  • Hair loss
  • Cold intolerance
  • Constipation

Hyperthyroidism can produce symptoms such as:

  • Sweating
  • Heart rate that is quite fast
  • Anxiety
  • Tremors
  • Fatigue
  • Sleeping problems 
  • Sudden weight loss
  • Eyes that protrude

If a pregnant woman has a known autoimmune thyroid illness, or if another autoimmune disorder is suspected, one or more thyroid antibodies may be ordered early in the pregnancy and again at the end. These tests are performed to see if the newborn is at risk for thyroid problems. Thyroid antibodies can pass the placenta, causing hypothyroidism or hyperthyroidism in a newborn or developing kid.

Thyroid antibody testing may also be recommended if a person with another autoimmune condition has thyroid dysfunction symptoms and/or has reproductive problems that a healthcare provider suspects are caused by autoantibodies.

What does a Thyroid Peroxidase blood test check for?

Thyroid Peroxidase is a thyroid antibody. Thyroid autoantibodies are antibodies that form when a person's immune system incorrectly attacks thyroid gland or thyroid protein components, causing chronic thyroid inflammation, tissue destruction, and/or thyroid function disruption. Specific thyroid autoantibodies in the blood are detected and quantified using laboratory techniques.

The thyroid gland is a tiny, butterfly-shaped gland in the throat that rests flat against the windpipe. Thyroxine and triiodothyronine, the two key hormones it generates, are critical in regulating the pace at which the body uses energy. Thyroid stimulating hormone stimulates the thyroid to generate T4 and T3 as needed by the body's feedback system. This mechanism aids in the maintenance of a reasonably constant level of thyroid hormones in the blood. Thyroid antibodies can cause chronic diseases and autoimmune disorders linked with hypothyroidism or hyperthyroidism, such as Graves disease or Hashimoto thyroiditis, when they interfere with this process.

Lab tests often ordered with a Thyroid Peroxidase test:

  • T3 Free
  • T3 Total
  • T4 Free
  • T4 Total
  • T3 Reverse
  • T3 Uptake
  • TSH
  • Thyroglobulin Antibodies

Conditions where a Thyroid Peroxidase test is recommended:

  • Hyperthyroidism
  • Hypothyroidism
  • Hashimotos
  • Graves’ Disease
  • Autoimmune Diseases
  • Thyroid Cancer

How does my health care provider use a Thyroid Peroxidase test?

Thyroid antibodies, such as thyroid peroxidase antibody, are tested to assist diagnose and differentiate autoimmune thyroid disease from other types of thyroid failure. Thyroid autoantibodies form when a person's immune system mistakenly targets thyroid gland or thyroid protein components, causing chronic thyroid inflammation, tissue destruction, and/or thyroid function disruption.

To aid in the diagnosis and/or monitoring of an autoimmune thyroid condition, one or more of the following tests may be used:

  • Thyroid peroxidase antibody is an antibody that attacks thyroid peroxidase and can be seen in Graves disease or Hashimoto thyroiditis.
  • Thyroglobulin antibody is an antibody that targets thyroglobulin, the thyroid hormone's storage form.

These tests may be conducted to determine the reason of an enlarged thyroid or other symptoms linked to low or high thyroid hormone levels. When other thyroid test findings, such as total or free T3, free T4, and/or TSH, indicate thyroid dysfunction, testing may be done as a follow-up.

A thyroid antibody test or several thyroid antibody tests may be conducted to see if a person with an autoimmune disorder is at risk of thyroid dysfunction. Disorders like systemic lupus erythematosus, rheumatoid arthritis, and pernicious anemia can cause this.

A thyroglobulin test may be used to monitor someone who is being treated for thyroid cancer. The thyroglobulin antibody test is utilized in this scenario to see if the antibody is present in the person's blood and will interfere with the thyroglobulin level test.

What do my thyroid antibody results mean?

Negative test results show that thyroid autoantibodies were not detected in the blood at the time of testing, implying that symptoms are caused by anything other than autoimmune disease. However, autoantibodies are absent in a small number of persons with autoimmune thyroid disease. Repeat testing may be done at a later date if it is suspected that the autoantibodies will develop over time, as with several autoimmune illnesses.

Thyroid antibodies can be identified in a range of thyroid and autoimmune conditions, including thyroid cancer, type 1 diabetes, rheumatoid arthritis, pernicious anemia, and autoimmune collagen vascular diseases, with mild to moderately high levels.

Thyroid autoimmune disorders such as Hashimoto thyroiditis and Graves disease are usually associated with significantly elevated amounts.

Thyroid antibodies, in general, indicate the presence of an autoimmune thyroid illness, and the higher the level, the more likely it is. Autoantibody levels that grow over time may be more relevant than steady levels because they may suggest an increase in the severity of autoimmune illness. All of these antibodies can increase the risk of hypothyroidism or hyperthyroidism in a growing baby or infant if they are present in a pregnant mother.

If a person with thyroid cancer has thyroglobulin antibodies, the testing for thyroglobulin levels may be hampered. This could suggest that the thyroglobulin test can't be utilized as a tumor marker or to track a person's thyroid cancer progression. The presence of thyroglobulin antibodies has little effect on some testing procedures, including mass spectrometry. The thyroglobulin test can be utilized as a tumor marker when tested in these methods, regardless of whether or not thyroglobulin antibodies are present. If a method is utilized that is impacted by thyroglobulin antibodies, the antibodies' levels can be used as a tumor marker to monitor thyroid cancer. If they first remain high or fall low but then rise over time, the treatment was ineffective and the malignancy is likely to continue or recur. If the levels are dropping and/or have dropped to low or undetectable levels, the therapy is more likely to have been successful in eradicating the malignancy.

Thyroid antibodies can be found in a small percentage of patients who are otherwise healthy. The incidence of these antibodies is higher in women, increases with age, and implies an increased risk of developing thyroid illness in the future for thyroid peroxidase antibodies. If a person has a thyroid antibody but no obvious thyroid disease, the healthcare professional will monitor the person's health over time. While the majority of people will never have thyroid problems, a small percentage will.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.

The following is a list of what is included in the item above. Click the test(s) below to view what biomarkers are measured along with an explanation of what the biomarker is measuring.

Also known as: Anti-Thyroid Microsomal Antibody, Anti-TPO, Thyroid Peroxidase Antibodies TPO, TPO

Thyroid Peroxidase

*Process times are an estimate and are not guaranteed. The lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance.

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