Thyroid Peroxidase (TPO) Antibodies

What is TPO Antibodies?

TPO, otherwise known as thyroid peroxidase, is an enzyme that usually exists in our thyroid gland. One of its major roles is to produce thyroid hormones. The thyroid gland is a butterfly-shaped one that is located in our throat. It produces many hormones such as T3 and T4. These two are very important to help the body use the energy it needs and metabolize properly. Our body resorts to a feedback system where a hormone called TSH controls the production of T4 and T3, as needed by the body. It helps stabilize the thyroid hormones in our blood.

Thyroid antibodies start forming when our immune system targets some parts of the thyroid gland or thyroid proteins, by mistake. As a result, chronic inflammation of the thyroid, referred to as thyroiditis, happens, along with many other conditions like tissue damage and degradation of thyroid function. This is called an autoimmune disorder that can be associated with hypothyroidism and hyperthyroidism. Such autoimmune conditions include Hashimoto thyroiditis and Grave’s disease.

Hashimoto thyroiditis’s exact causes are not fully understood. But, many risk factors can contribute to such a diagnosis like having the genetic component of the disease. Gender plays a major role in the incidence of this condition: women are seven times more likely to suffer from it. Many drugs and having a high Iodine intake can trigger malfunctions of the thyroid gland, especially among those who are already susceptible.

Grave’s disease is an illness that causes an overactivity of the thyroid gland. Like Hashimoto disease, it is more common among women than men. What causes our immune system to attack the thyroid gland, in this case, is the production of antibodies like TSI and TRAb that order the thyroid cells to overwork themselves.

Why take the TPO Antibodies test?

TPO are antibodies that exist in the follicle cells of the thyroid gland. TPO is the most common test to detect an autoimmune disease of the thyroid gland like the Hashimoto and Grave’s disease.

If you have symptoms of Hashimoto Thyroiditis; then, you are advised to order the TPO Antibody test. These include weight gain, fatigue, having a pale and puffy face, constipation, experiencing unexplained joint and muscle pains, having brittle hair, depression and having a slow heart rate. Since these symptoms can be similar to other health conditions, it is essential to get your TPO Antibodies tested and have the right diagnosis and treatment plan.

You need to get your TPO Antibodies tested if you experience symptoms of Grave’s disease that consist of a racing heartbeat, hand tremors, trouble sleeping, losing weight, feeling the muscles weak, as well as having bulging eyes. Skin symptoms can also accompany this auto-immune disease, and consist of developing a dermopathy: development of lumpy red thick skin in front of the shins.

The TPO Antibodies test is also ordered to monitor the treatment of thyroid cancer. From another angle, it is encouraged to be taken in case the person is having reproductive difficulties like miscarriages, pre-eclampsia, premature delivery and in-vitro fertilization.

While TPO Antibodies are used to detect thyroid malfunctions, in many cases, it is used to detect an underlying risk for a possible future thyroid problem. According to Mayo Clinic, if you have your thyroid hormones within normal ranges but have TPO antibodies, you may need to get a periodic check-up of your thyroid function.

What your TPO Antibodies test results mean?

The normal range for TPO Antibodies is less than 35 IU/mL.

A null to minimal TPO Antibody test means that your blood does not contain TPO antibodies. This normally insinuates that the causes of your thyroid symptoms are not due to an auto-immune disease. However, if these conditions are suspected; then, a recurring test may be recommended.

When the levels are mildly elevated, this can be caused by many thyroid conditions like thyroid cancer, type-1 diabetes, rheumatoid arthritis, as well as auto-immune collagen vascular disease.

High levels of TPO Antibodies are usually caused by an autoimmune disease like the Hashimoto Thyroiditis, Graves Disease, pernicious anemia, lupus and rheumatoid arthritis. It has been reported that almost 3% of people who have a positive TPO test result do not show any symptom.

If levels are high in a pregnant woman, this may lead to higher risks of developing hypothyroidism or hyperthyroidism in the newborn baby.

Where can I get a TPO Antibodies test near me?

Please use our Lab Locator to find find a convenient testing location.

Reviewed By: Dr. Kurt Kloss, MD
Last Reviewed Date: Mar 12, 2020