Thyroglobulin Antibody Test

A thyroglobulin antibody test measures antibodies against thyroglobulin, a protein found in thyroid cells. In people with an autoimmune thyroid condition, the immune system mistakenly produces antibodies that attack this protein as if it were an invader.

A thyroglobulin antibody test may be performed if your healthcare provider suspects you have a thyroid condition. The test might be ordered along with other thyroid tests such as a thyroid stimulating hormone (TSH) test.

This article discusses the thyroglobulin antibody test, why it is done, and what its results can tell you.

What Is a Thyroglobulin Antibody Test For?

Thyroglobulin is a protein that helps your thyroid synthesize T4 and the active T3 form of thyroid hormones. These hormones play an important role in your body’s metabolism, growth, and development.

A thyroid autoimmune disease can cause your thyroglobulin levels to fall outside the normal range. This happens when your immune system mistakenly attacks thyroglobulin.

If your healthcare provider thinks you have a thyroid problem, they may order a thyroglobulin antibody test. This test is also called an antithyroglobulin antibody test or thyroid antibody test. If the test finds antithyroglobulin antibodies in your bloodstream, it's an indication that you may have an autoimmune condition affecting the thyroid, such as:     

• Overactive thyroid or Grave’s disease
• Hashimoto thyroiditis
• Underactive thyroid or hypothyroidism
  
• Type 1 diabetes
• Systemic lupus erythematosus

Thyroglobulin antibodies are also useful in monitoring thyroid cancer patients after the removal of the thyroid gland. The presence of antibodies after a thyroidectomy may mean there's new thyroid tissue growing, and possibly a thyroid cancer reoccurrence.

Antibodies to thyroglobulin may decrease with time after total thyroidectomy. They may also make it more challenging to monitor thyroglobulin levels as an indicator of thyroid cancer recurrence.

Purpose of the Test

Thyroid antibodies are destructive to the thyroglobulin protein, so your healthcare provider may order a thyroglobulin antibody test to gain a clearer understanding of what could be causing you to feel unwell. Symptoms that could indicate a possible underactive thyroid condition include:

• Fatigue
• Dry skin, hair, and nails
• Weight gain
• Digestive problems (especially constipation)
• Constantly feeling cold
• Menstrual irregularities
• Depression
• Decreased sweating
• Forgetfulness or brain fog
• Joint or muscle pain

Symptoms that may indicate an overactive thyroid include:

• Fatigue (can be present when the thyroid is under or overactive)
• Feeling weak
• Unexplained weight loss
• Feelings of anxiousness, anxiety, or irritability
• Increased sweating
• Heat intolerance
• Rapid heart rate or changes in heart rhythm
• Feeling shaky

Additionally, the thyroglobulin antibody test may be ordered in conjunction with other thyroid blood tests, including

• Thyroid-stimulating hormone (TSH)
• T4 hormone (also known as thyroxine)
• T3 hormone (also known as triiodothyronine)
  

Before the Test

Be sure to tell your healthcare provider about any medications, herbs, and supplements (including over-the-counter ones) you’re taking.

Your healthcare provider will provide you with specific instructions for taking this blood test, but you will most likely need to avoid eating and drinking for several hours (or overnight) before having your blood drawn.

On the day of the test, wear a short-sleeve shirt or something with sleeves you can roll or pull up, which will allow for access to the veins in your arms. Also, be sure to bring your insurance card and a form of identification with you so that the healthcare facility can bill your insurance carrier. Keep in mind that reimbursement for testing varies among insurance companies, so you may need to speak to your carrier to determine if you need pre-approval when having a thyroglobulin antibody test.

During the Test

If you’ve had your blood drawn before, this test will be very similar to a traditional blood draw. At most labs, you’ll be seated in a chair with one arm resting in front of you to draw the blood. The lab technician, nurse, or another healthcare provider will wrap an elastic band around your arm to temporarily restrict blood flow and locate a vein. Then, they will disinfect the area with alcohol using an alcohol swab or pad.

Next, the needle will be inserted into your arm, and a tube that collects the blood sample will be placed at the base of the syringe. Once enough blood is drawn for the test, the lab technician will loosen the elastic band, remove the needle, and place a bandage over the insertion site.

After the Test

After the test, your healthcare provider will let you know when it’s okay to resume eating and taking your medications. Your arm may feel a bit sore where the blood was taken, but it should go away in a day or two. Otherwise, you can usually go back to your normal activities and await any specific follow-up instructions from your healthcare provider.  

Interpreting the Results

The reference range for the tests can differ from one lab to another.

But if your test is positive, meaning antibodies were present in your blood, this could indicate there’s a problem with your thyroid glands such as hypothyroidism, Grave’s disease, Hashimoto’s thyroiditis, or another condition. Be sure to speak to your healthcare professional, who can help you understand your results and any underlying health issues.

Risks and Contraindications

The risks associated with a thyroglobulin antibody test are considered minimal and are comparable to those of other blood tests you might have had done before. Occasionally, your healthcare provider or technician can have some difficulties getting a sample on the first try because some veins can be hard to locate, or may shift positions during the draw.

In a circumstance like this, the needle would need to be inserted another time to obtain a sample. Additionally, you may experience mild pain, bruising, or a stinging sensation at the insertion of the needle, but the discomfort should subside quickly.

If you are prone to feeling faint or lightheaded whenever your blood is taken, feel free to tell your nurse or technician so that you can remain seated in the chair for a few extra minutes or have the blood test done in a lying position.

Summary

A thyroglobulin antibody test looks for antibodies against a protein called thyroblobulin. The presence of these antibodies could mean you have an autoimmune condition that affects the thyroid, such as Hashimoto's disease or Grave's disease.

This test involves drawing blood and sending it to a laboratory for analysis. It is often done alongside other tests such as a thyroid stimulating hormone (TSH) test.