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Thyroid Antibodies

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Also known as: Thyroid Autoantibodies; Antithyroid Antibodies; Antimicrosomal Antibody; Thyroid Microsomal Antibody; Thyroid Peroxidase Antibody; Thyroperoxidase Antibody; TPO; Anti-TPO; TBII; Antithyroglobulin Antibody; TgAb; TSH Receptor Antibody; TRAb; Thyrotropin Receptor Antibodies; Thyroid Stimulating Immunoglobulin; TSI
Formal name: Thyroid Peroxidase Antibody; Thyroglobulin Antibody; Thyroid Stimulating Hormone Receptor Antibody

The Test Sample

What is being tested?

Thyroid autoantibodies are antibodies that develop when a person's immune system mistakenly targets components of the thyroid gland or thyroid proteins, leading to chronic inflammation of the thyroid (thyroiditis), tissue damage, and/or disruption of thyroid function. Laboratory tests detect the presence and measure the quantity of specific thyroid autoantibodies in the blood.

Location of the thyroidThe thyroid is a small, butterfly-shaped gland that lies flat against the windpipe in the throat. The primary hormones that it produces, thyroxine (T4) and triiodothyronine (T3), are vital in helping to regulate the rate at which the body uses energy (metabolism). The body uses a feedback system in which thyroid stimulating hormone (TSH) stimulates the thyroid to produce T4 and T3 as needed. This system helps maintain a relatively stable amount of the thyroid hormones in the blood. When thyroid antibodies interfere with this process, they can lead to chronic conditions and autoimmune disorders associated with hypothyroidism or hyperthyroidism, such as Graves disease or Hashimoto thyroiditis.

Thyroid antibody tests include:

  • Thyroid peroxidase antibody (TPO)
  • Thyroglobulin antibody (TGAb)
  • Thyroid stimulating hormone receptor antibodies (TSHRAb), including thyroid stimulating immunoglobulin (TSI) and thyroid binding inhibitory immunoglobulin (TBII)

For more on these, see the "How is it used?" section.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.