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February 9, 2012

Thyroid Peroxidase Test

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What is thyroid peroxidase?

Thyroid peroxidase (TPO) is an enzyme made in the thyroid gland that is important in the production of thyroid hormone. TPO is found in thyroid follicle cells where it converts the thyroid hormone T4 to T3.

The thyroid gland is located in the lower part of the neck, below the Adam's apple, wrapped around the trachea (windpipe).

Picture of the thyroid gland

What is the thyroid peroxidase test?

Thyroid peroxidase test is a test that measures the level of an antibody that is directed against thyroid peroxidase (TPO).

Autoantibodies to thyroid peroxidase (TPOAb) are produced within the body. The presence of TPOAb in the blood reflects a prior attack on the thyroid tissue by the body's immune system.

What does a positive thyroid peroxidase test mean?

  • Most people with chronic thyroiditis (70%-90%) display a positive TPO test. The test is also positive in lesser numbers of people with other thyroid diseases.

  • Other autoimmune disorders that may cause a positive TPOAb test include:

  • About 3% of people with a positive TPOAb test show no evidence of disease.

  • The chance of having a positive TPOAb test is greater in females and increases with age.



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Thyroid Peroxidase Test

Introduction

The thyroid gland produces hormones that are essential for normal body metabolism. Blood testing is now commonly available to determine the adequacy of the levels of thyroid hormones. These blood tests can define whether the thyroid gland's hormone production is normal, overactive, or underactive.

What are thyroid hormones?

Thyroid hormones are produced by the thyroid gland. This gland is located in the lower part of the neck, below the Adam's apple. The gland wraps around the windpipe (trachea) and has a shape that is similar to a butterfly - formed by two wings (lobes) and attached by a middle part (isthmus).

The thyroid gland uses iodine (mostly available from the diet in foods such as seafood, bread, and salt) to produce thyroid hormones. The two most important thyroid hormones are thyroxine (T4) and triiodothyronine (T3), which account for 99.9% and 0.1% of thyroid hormones pre...

Read the Thyroid Blood Tests article »







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