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Antithyroglobulin Antibody Test

What is an antithyroglobulin antibody test?

Your thyroid is a gland located in your neck. It releases hormones that control your metabolism. It produces a number of different proteins, including thyroglobulin. Your thyroid uses thyroglobulin to make the active thyroid hormones.

If you have an autoimmune condition, it can disrupt your production of thyroglobulin. An autoimmune condition happens when your immune system creates antibodies that attack your body’s own healthy cells. When your immune system attacks the thyroid, it often targets thyroglobulin. This causes it to produce antithyroglobulin antibodies. Your doctor can order an antithyroglobulin antibody test to check the level of these antibodies in your bloodstream. A high level may indicate an autoimmune condition

Why is an antithyroglobulin antibody test ordered?

Your doctor may order an antithyroglobulin test if you have symptoms of a thyroid disorder, such as:

  • fatigue
  • unexplained weight gain
  • constipation
  • dry skin

Your doctor may also order it if you develop a goiter, a condition that happens when your thyroid gland becomes enlarged. They may also order it if they suspect you have an autoimmune disorder, such as Graves' disease or Hashimoto thyroiditis. It can help them check for impaired thyroid function.

How should you prepare for the test?

For an antithyroglobulin antibody test, you will need to have a sample of your blood drawn. Your doctor will tell you how to prepare. They may ask you to avoid eating or drinking anything for several hours beforehand. They may also ask you to stop taking certain medications that may interfere with your test results or blood draw. For example, they may ask you to avoid taking blood thinners, such as warfarin or even multivitamins.

Tell your doctor about all medications that you take, including prescription and over-the-counter drugs. Don’t stop taking your medications without talking to your doctor about it first.

How is the test administered?

A nurse or lab technician will draw a sample of your blood in a clinical setting. They will likely use a small needle to draw it from a vein in your arm. They will collect it in a tube and send it to a lab for testing. Your doctor will let you know when your test results are available.

What are the risks of the test?

For most people, this test involves minimal risks. They’re common to all routine blood tests. For example, you may experience discomfort when your blood is drawn. You may develop some pain, throbbing, or bruising at the puncture site. If the nurse or technician has trouble drawing a sample of your blood, they may need to inject the needle multiple times.

Other risks include:

  • lightheadedness or fainting
  • excessive bleeding at the puncture site
  • accumulation of blood under your skin, known as a hematoma
  • development of an infection where your skin is broken by the needle
  • inflammation of your vein, known as phlebitis

For most people, the potential benefits of the test outweigh the risks.

What do the test results mean?

Normal results for this test are "negative." If you receive negative results, that means no antithyroglobulin antibodies were found in your blood sample. If you do have small amounts in your blood, it may be a sign of certain health problems, such as:

If you have high levels of antithyroglobulin antibodies in your blood, it may be a sign of serious autoimmune disorder, such as Graves’ disease or Hashimoto thyroiditis.

In some cases, you may have antithyroglobulin antibodies in your blood without any specific complications. If you test positive for these antibodies, and your doctor can’t identify an underlying cause, they may monitor you for emerging health problems.

Your doctor can help you understand the results of your test. Your recommended follow-up steps will depend on your specific diagnosis. For example, they may recommend additional tests or treatment options. Ask your doctor for more information about your test results, condition, and next steps.

Content licensed from:

Written by: Darla Burke
Medically reviewed on: Jan 04, 2017: University of Illinois-Chicago, College of Medicine

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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