Thyroid antibodies

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Also known as: Thyroid autoantibodies; antithyroid antibodies; antimicrosomal antibody; thyroid microsomal antibody; thyroperoxidase antibody; TPOAb; anti-TPO; antithyroglobulin antibody; TgAb; TSH receptor antibody; TRAb; thyroid stimulating immunoglobulin; TSI; TBII
Formal name: Thyroid peroxidase antibody (TPOAb); thyroglobulin antibody (TgAb); and thyroid stimulating hormone receptor antibody (TRAb)

At a Glance

Why Get Tested?

To help diagnose and monitor autoimmune thyroid diseases and to distinguish these from other forms of thyroiditis; 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 FT3, FT4, and TSH) indicate thyroid dysfunction; along with a thyroglobulin test when your doctor is using it as a monitoring tool; at intervals recommended by your doctor when you have a known autoimmune thyroid disorder

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None

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 recognises components of the thyroid as foreign (not-self), which 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 – metabolism. 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) such as Hashimto thyroiditis or hyperthyroidism (excessive amounts of thyroid hormones) seen in Graves' disease. 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

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

No test preparation is needed.

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.