Autoantibody Testing

What is autoantibody testing?

Autoantibody testing checks a sample of your blood for autoantibodies, proteins made by the immune system.

Normally, your immune system makes proteins called antibodies to attack germs that could make you sick. Autoantibodies, however, do not attack germs. They instead attack your own healthy tissue and organs, believing them to be foreign substances. This can lead to the development of an autoimmune disease. There are more than 80 types of autoimmune diseases, and they can affect almost any part of your body.

Your immune system makes autoantibodies by mistake. Researchers aren't entirely sure why, though your body is more likely to make them if you:

• Have a family history of autoimmune diseases.
• Have a viral or bacterial infection, especially if it's chronic (long-term). This can cause your immune system to be overactive, which can lead to the production of autoantibodies.
• Are exposed to certain environmental toxins.

There are many different types of autoantibodies, and they can affect your body in different ways. Some affect only specific organs and/or parts of your body. These are called organ-specific antibodies. For example:

• Thyroid antibodies, such as anti-TPO, only affect your thyroid.
• Smooth muscle antibodies (SMAs) attack smooth muscle, usually in the liver.
• Islet cell autoantibodies attack cells in your pancreas.

Other antibodies, however, affect multiple organs and can cause a variety of symptoms. These are called systemic antibodies. This type can include:

• Antinuclear Antibody (ANA).
• Antineutrophil Cytoplasmic Antibodies (ANCA).
• Anti-Double Stranded DNA (anti-dsDNA).
• Antihistone Antibodies.
• Rheumatoid Factor (RF).

Other names: antibody serology test, antinuclear antibody (ANA) test, extractable nuclear antigen (ENA) test, anti-dsDNA test, rheumatoid factor (RF) test, antineutrophil cytoplasmic antibodies (ANCA) test, smooth muscle antibody (SMA) test, thyroid antibody test

What is autoantibody testing used for?

Every autoantibody test is used to help diagnose or monitor an autoimmune disease. However, because the types of autoantibodies can vary, there are different types of autoantibody tests. Some of these can be used to diagnose autoimmune conditions that affect only one organ. For example:

• Thyroid antibody tests look for thyroid-specific antibodies and can be used to help diagnose Grave's Disease and Hashimoto's Disease.
• Smooth muscle antibody (SMA) tests look for smooth muscle antibodies and can be used to help diagnose autoimmune hepatitis.
• Tissue transglutaminase antibody (tTG) tests look for the tTG antibody and can be used to help diagnose celiac disease.

Other tests can be used to diagnose autoimmune conditions that affect multiple organs. For example:

• Anti-dsDNA tests look for the anti-dsDNA autoantibody and can be used to help diagnose lupus.
• Rheumatoid factor (RF) tests look for rheumatoid factor and can be used to help diagnose rheumatoid arthritis.
• Antineutrophil cytoplasmic antibodies (ANCA) tests look for ANCA in your blood and can be used to help diagnose autoimmune vasculitis.

However, some autoantibody tests look for a wider range of autoantibodies. The most common of these are the antinuclear antibody (ANA) test and the extractable nuclear antigen (ENA) test. These tests can be used to help diagnose many of the conditions listed above, as well as:

• Sjogren's syndrome.
• Polymyositis and dermatomyositis.
• Addison Disease.
• Mixed connective tissue disease.
• Scleroderma.
• Type 1 diabetes.
• Psoriasis and psoriatic arthritis.
• Raynaud's Phenomenon.

If your provider is using autoantibody tests to help make a diagnosis, they may also consider:

• The results of any imaging scans, such as x-rays.
• Biopsy results.
• Your physical symptoms.
• Your family and health history.

The results of an autoantibody test alone are usually not enough to make a diagnosis.

Why do I need autoantibody testing?

You may need autoantibody testing if you have symptoms commonly associated with some autoimmune diseases. The symptoms of an autoimmune disease depend on the part of your body that's affected. These can include:

• Fever.
• Fatigue.
• Joint symptoms, including pain and swelling.
• Muscle pain or weakness.
• Swollen glands.
• Abdominal (belly) pain and/or cramps.
• Rashes that can't be explained.
• Unexpected weight loss or gain.
• Palpitations (racing or pounding heart).
• Anxiety and depression.
• Seizures.

Other illnesses can, however, cause the same symptoms. Symptoms for many autoimmune conditions may also come and go.

You may also need an autoantibody test if you've been diagnosed with an autoimmune disease, and your provider wants to monitor your condition. For example, a provider may order an islet autoantibodies test if they want to monitor your Type 1 diabetes, which is a type of organ-specific autoimmune disease.

What happens during autoantibody testing?

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 autoantibody testing?

You don't need any special preparations for autoantibody testing.

Are there any risks to autoantibody testing?

There is very little risk to 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 depend on the type of autoantibody test you had. But generally, your results will be either positive or negative.

• A negative (normal) result means that you have little or no autoantibodies in your blood. But that doesn't rule out an autoimmune disease. People with rheumatoid arthritis, for example, may have little to no RF in their blood. If you have symptoms of an autoimmune disease, but your results are normal, your provider may order more tests to make a diagnosis.
• A positive (abnormal) result means that some amount of autoantibodies were found in your blood. This doesn't necessarily mean that you have an autoimmune disease. Some healthy people have autoantibodies in their blood. To make a diagnosis, your provider will consider other test results along with your symptoms and medical history.

Some results may give a number for how many autoantibodies were found. This is called a titer. If a titer is provided, your results will also have a reference range. A reference range is a set of numbers that form the high and low ends of the range of results that's considered normal. So, a titer value that is higher than the reference range may be a sign of an autoimmune disease.

The results for autoantibody panels, such as ANA and ENA tests, might also go into detail for each of the autoantibodies tested. This means you could have positive results for some autoantibody tests and negative results for others.

Because autoantibody test results can mean so many different things, it's important to talk to your provider about what your results mean for you.

Learn more about laboratory tests, reference ranges, and understanding results.