Thyroid antimicrosomal antibody; Antimicrosomal antibody; Microsomal antibody; Antithyroid microsomal antibody; TPOAb; Anti-TPO antibody
Thyroid peroxidase is a type of protein (called an enzyme) that cells in the thyroid gland use to make thyroid hormone. If these enzymes leak out into the bloodstream (as when thyroid cells are damaged) the immune system makes antibodies against these proteins. The thyroid peroxidase antibody test measures these antibodies in the blood.
A blood sample is needed.
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
This test is done to confirm the cause of thyroid problems, including Hashimoto thyroiditis.
The test is also used to find out if an immune or autoimmune disorder is damaging the thyroid.
A negative test means the result is normal.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different specimens. Talk to your health care provider about the meaning of your specific test results.
A positive test may be due to:
High levels of these antibodies have also been linked with an increased risk of:
Important: A positive result does not always mean that you have a thyroid condition or that you need treatment for your thyroid. A positive result may mean that you have a higher chance of developing thyroid disease in the future. This is often associated with a family history of thyroid disease.
Antithyroid microsomal antibodies may be seen in your blood if you have other autoimmune conditions, including:
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
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BACK TO TOPReview Date: 2/28/2024
Reviewed By: Sandeep K. Dhaliwal, MD, board-certified in Diabetes, Endocrinology, and Metabolism, Springfield, VA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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