What is a thyroid antibodies test?
This test measures the level of thyroid antibodies in your blood. The thyroid is a small, butterfly-shaped gland located near the throat. Your thyroid makes hormones that regulate the way your body uses energy. It also plays an important role in regulating your weight, body temperature, muscle strength, and even your mood.
Antibodies are proteins made by the immune system to fight foreign substances like viruses and bacteria. But sometimes antibodies attack the body’s own cells, tissues, and organs by mistake. This is known as an autoimmune response. When thyroid antibodies attack healthy thyroid cells, it can lead to an autoimmune disorder of the thyroid. These disorders can cause serious health problems if not treated.
There are different types of thyroid antibodies. Some antibodies destroy thyroid tissue. Others cause the thyroid to make too much of certain thyroid hormones. A thyroid antibodies test usually measures one or more of the following types of antibodies:
- Thyroid peroxidase antibodies (TPO). These antibodies can be a sign of:
- Hashimoto disease, also known as Hashimoto thyroiditis. This is an autoimmune disease and the most common cause of hypothyroidism. Hypothyroidism is a condition in which the thyroid doesn’t make enough thyroid hormones.
- Graves’ disease. This is also an autoimmune disease and the most common cause of hyperthyroidism. Hyperthyroidism is a condition in which the thyroid makes too much of certain thyroid hormones.
- Thyroglobulin antibodies (Tg). These antibodies can also be a sign of Hashimoto disease. Most people with Hashimoto disease have high levels of both Tg and TPO antibodies.
- Thyroid-stimulating hormone (TSH) receptor. These antibodies can be a sign of Grave’s disease.
Other names: thyroid autoantibodies, thyroid peroxidase antibody, TPO, Anti-TPO, thyroid- stimulating immunoglobulin, TSI
What is it used for?
A thyroid antibodies test is used to help diagnose autoimmune disorders of the thyroid.
Why do I need a thyroid antibodies test?
You may need this test if you have symptoms of a thyroid problem and your provider thinks they may be caused by Hashimoto disease or Grave’s disease.
Symptoms of Hashimoto disease include:
- Weight gain
- Hair loss
- Low tolerance for cold temperatures
- Irregular menstrual periods
- Joint pain
Symptoms of Grave’s disease include:
- Weight loss
- Bulging of the eyes
- Tremors in the hand
- Low tolerance for heat
- Trouble sleeping
- Increased heart rate
- Swollen thyroid, known as goiter
You may also need this test if other thyroid tests show that your thyroid hormone levels are too low or too high. These tests include measurements of hormones known as T3, T4, and TSH (thyroid-stimulating hormone).
What happens during a thyroid antibodies test?
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Will I need to do anything to prepare for the test?
There are no special preparations necessary for a thyroid antibodies blood test.
Are there any risks to the test?
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
What do the results mean?
Your results may show one of the following:
- Negative: no thyroid antibodies were found. This means your thyroid symptoms are probably not caused by an autoimmune disease.
- Positive: antibodies to TPO and/or Tg were found. This may mean you have Hashimoto disease. Most people with Hashimoto disease have high levels of one or both of these types of antibodies.
- Positive: antibodies to TPO and/or TSH receptor were found. This may mean you have Grave’s disease.
The more thyroid antibodies you have, the more likely it is that you have an autoimmune disorder of the thyroid. If you are diagnosed with Hashimoto disease or Grave’s disease, there are medicines you can take to manage your condition.
Is there anything else I need to know about a thyroid antibodies test?
Thyroid disease can get worse during pregnancy. This can harm both the mother and her unborn baby. If you have ever had thyroid disease and are pregnant, you may be tested for thyroid antibodies along with tests that measure thyroid hormones. Medicines to treat thyroid disease are safe to take during pregnancy.