The Thyrotropin Receptor Antibody Test

A Blood Test for Autoimmune Thyroid Disease

The thyrotropin receptor antibody (TRAb) test is a blood test that helps doctors diagnose the autoimmune thyroid condition called Graves' Disease. The antibodies it tests for are present in 90% of the people who have this disease.

Other names for the TRAb test include:

  • Anti-Thyrotropin
  • Anti-TSHR
  • Antibodies to TSH receptor
  • Inhibitory Immunoglobulin
  • TBII
  • TBII (Thyrotropin-Binding Inhibitory Immunoglobulin)
  • Thyroid Stimulating Immunoglobulin
  • Thyroid-Stimulating Hormone Receptor (TSH Receptor) Antibody
  • Thyrotropin Receptor Antibody
  • TRAb
  • TSH Receptor Antibody
  • TSH Receptor Blocking Antibody

Purpose of Test

Your doctor may send you for a TRAb test if you have symptoms that are consistent with hyperthyroidism (an over-active thyroid gland) or Graves' Disease, which is the cause of thyroid over-activity more than 70% of the time hyperthyroidism is diagnosed. These symptoms include:

  • Unexplained weight loss
  • Anxiety and/or irritability
  • Heat intolerance (feeling hot when the people around you are cold)
  • Excessive sweating
  • Muscle weakness
  • Hair loss
  • Unusually smooth skin
  • Rapid, irregular heartbeat
  • Fatigue
  • Goiter (a lump in the front of your neck where the thyroid gland is that you can see or feel)

These are some of the major symptoms, but hyperthyroidism can cause many other symptoms as well.

A few symptoms are associated with Graves' disease but not other forms of hyperthyroidism. Not everyone has them, but when they're present, they make Graves' more highly suspected. They are:

  • Bulging eyes (called Graves' ophthalmopathy)
  • Skin lesions (called thyroid dermopathy), which cause swelling and severe itching

What the TRAb Test Looks for

The TRAb test detects the autoantibody that's associated with Graves' disease. An antibody is a specialized protein made by your immune system. Antibodies are custom made to kill pathogens in your body, such as viruses or bacteria.

An autoantibody is a mistake—your immune system has wrongly identified a healthy tissue as a pathogen and seeks to destroy it.

Thyrotropin is also called thyroid-stimulating hormone, or TSH. TSH binds to receptors on the thyroid gland to tell it to produce thyroid hormone. The thyrotropin receptor antibody mimics TSH, so when it's present, it directs the thyroid to keep releasing hormone when your body doesn't need it. That results in high levels of thyroid hormones, which is what causes symptoms. If the thyrotropin receptor antibody is present, it's an indicator of Graves' disease.

Limitations of the Test

Because this autoantibody is only present in 90% of people with Graves', a negative test doesn't automatically rule out the disease. Your doctor will have to rely on the symptoms you report as well as other tests in order to make a diagnosis.

The TRAb test has seen some controversy over how accurate it is. An analysis of research on the subject, though, finds that the science behind the test has come a long way. Now on its third generation, researchers said that better testing has provided a springboard for better, individualized treatment.

Other Common Tests

Along with the TRAb, your doctor may order a number of blood tests to help diagnose you. In someone who has symptoms consistent with hyperthyroidism, those tests are likely to include:

  • TSH
  • Thyroxine (T4)
  • Triiodothyronine (T3)

Doctors may also request one or more of the following imaging tests since Graves' can alter the appearance of the thyroid gland:

If testing leaves uncertainty about your diagnosis or your doctor suspects thyroid cancer, you may be sent for a biopsy. That allows the tissue to be examined under a microscope.

Risks and Contraindications

Blood tests are common and quite safe. You may feel a sting from the needle. Afterward, you may have a small red mark where the needle was inserted, and sometimes the area can bruise. Keep the injection site clean as you would any cut or scrape.

Long-Term Effects

Simple blood tests like those performed for hyperthyroidism are not associated with any long-term effects.

Contraindications

If you have a bleeding disorder, cellulitis, or problems with your veins, let your doctor know before you go for blood tests.

Before the Test

You shouldn't need to go without food or drink or prepare in any way before your TRAb or other thyroid-hormone tests. These tests can typically be performed at any time of day.

For any blood draw, it's important that you're hydrated—both for your own sake and to make the procedure easier.

Location and Timing

A blood draw for a TRAb is sometimes done by a nurse in your doctor's office, but you may be sent to a lab. The test itself takes very little time—just a couple of minutes.

However, when you go in for the test, you may have to fill out forms and/or wait for the lab tech to get to you. If you're concerned about how much time it will take, call the lab to check on wait times or ask what time of day is usually fastest.

If you're anxious about the test, you may want to give yourself extra time in case you suffer negative effects from the anxiety, such as dizziness or a panic attack. You may also want to arrange for someone to drive you to and from the test.

You probably will not get the results of your TRAb right away. It's more likely that your doctor will contact you later with the results. You may want to ask the doctor how long it should take to hear from them and check with the office if it seems like you've waited too long. Expect it to take at least several days.

What to Wear

You'll want to wear short sleeves or sleeves that can easily be pushed or rolled up. You shouldn't need to change into a hospital gown for a TRAb.

Cost and Health Insurance

Your health insurance may require pre-approval before you get a TRAb test, so be sure to check with the company. You may have a copay or be responsible for a portion of the cost. Your doctor's office or the lab should be able to tell you the price before the test.

What to Bring

When you go to be tested, be sure you have your insurance card and any paperwork your doctor may have given you regarding the test. You may want to bring something to occupy your time if you expect a long wait.

During the Test

The test procedure is fairly simple. Here's what to expect.

Pre-Test

The nurse or phlebotomist who draws your blood may ask you to confirm your name, birth date, and other information to ensure there's no mix-up and everything is properly labeled.

They'll ask you to push up your sleeve or remove a long-sleeved layer if necessary. Then they'll tie something around your upper arm to trap blood in the vein they're planning to use and swab the site with alcohol to clean it. They may ask you to make a fist or squeeze your hands open and closed.

Throughout the Test

They'll then insert the needle and release the tourniquet on your arm to encourage blood flow. If multiple tests are being performed on your blood, they may then switch out vials one or more times. Once the requisite blood is withdrawn, they'll slip the needle out and put pressure on the site to stop the bleeding.

Post-Test

After that, they'll bandage it and you should be free to go. If you're having any problems, such as anxiety or dizziness, let them know. They may want to monitor you for a while to make sure it's safe for you to leave.

After the Test

You may have a little soreness around the site, and it may bruise a little, which is normal. The bruise should go away in a few days.

You shouldn't have any other lingering effects from a simple blood draw. If you experience any other adverse effects, call your doctor.

Interpreting Results

TRAb test results are pretty simple to interpret—if you test positive for the autoantibodies, you have Graves' disease. If not, your doctor may do other tests to determine whether you have Graves' or another condition, depending on how your other thyroid hormone levels are.

Follow-Up

Once you've received your results, you may need to go back to the doctor to discuss treatment options or for further testing, if results were negative or inconclusive.

A Word From Verywell

The diagnostic process can be scary and confusing. It also tends to happen more slowly than we'd like when we're not feeling well and concerned about our health. A diagnosis of a chronic disease can be frightening as well. Throughout the process, try to keep in mind that getting the right diagnosis is better than getting a rushed (and possibly incorrect) one. Once you are diagnosed, even if the news isn't what you'd hoped, the upside is that you can start exploring treatment options so that you can feel better.

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Article Sources

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