Thyroid Antibodies

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Also known as: Thyroid autoantibodies; Anti-thyroid antibodies; Anti-microsomal antibody; Thyroid microsomal antibody; Thyroid peroxidase antibody; TPOAb; Anti-TPO; TBII; Antithyroglobulin antibody; TgAb; TSH receptor antibody; TRAb; Thyroid stimulating immunoglobulin; TSI
Formal name: Thyroid peroxidase antibody (TPOAb); Thyroglobulin antibody (TgAb); Thyroid stimulating hormone receptor antibody (TRAb)
Related tests: Free T3; Free T4; TSH; Thyroglobulin

At a Glance

Why Get Tested?

To help diagnose and monitor autoimmune thyroid diseases and to distinguish these from other forms of thyroiditis, and thyroid disease; to help guide treatment decisions

When to Get Tested?

If you have an enlarged thyroid gland (goitre) and/or if your other thyroid tests (such as Free T3, Free T4, and TSH) indicate thyroid dysfunction; if there are clinical features to suggest thyroid disease; in some patients with related autoimmune diseases

Sample Required?

A blood sample taken from a vein in your arm

The Test Sample

What is being tested?

These tests detect the presence and measure the quantity of specific thyroid autoantibodies. These develop when a person’s immune system mistakenly recognizes components of the thyroid as foreign (not-self) and can lead to chronic thyroiditis (inflammation of the thyroid), tissue damage, and disruption of thyroid function. 

The 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 we use energy. The body has a feedback system that utilises thyroid stimulating hormone (TSH) to help turn thyroid hormone production on and off and maintain a stable amount of the thyroid hormones in the bloodstream. When thyroid antibodies interfere with this process, it can lead to chronic conditions and disorders associated with hypothyroidism (not enough thyroid hormones) or hyperthyroidism (excessive amounts of thyroid hormones). Hypothyroidism can cause symptoms such as weight gain, fatigue, goitre (enlarged thyroid gland), dry skin, hair loss, intolerance to cold, and constipation. Hyperthyroidism can cause symptoms such as sweating, rapid heart rate, anxiety, tremors, fatigue, difficulty sleeping, sudden weight loss, and protruding eyes.

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.

The Test

Common Questions

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.