Antineutrophil Cytoplasmic Antibodies (ANCA) Test

What is an antineutrophil cytoplasmic antibodies (ANCA) test?

An ANCA test looks for antineutrophil cytoplasmic antibodies (ANCA) in a sample of your blood. Antibodies are proteins that your immune system makes to fight foreign substances, such as viruses and bacteria. ANCAs, however, are autoantibodies, which are antibodies that attack your own healthy tissues and organs by mistake. This can lead to the development of an autoimmune disease.

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 two main kinds of ANCA called pANCA and cANCA. Each type targets a specific protein inside neutrophils (a type of white blood cell). An ANCA test can show whether you have one or both types of antibodies.

Other names: ANCA antibodies, cANCA, pANCA, cytoplasmic neutrophil antibodies, serum, anticytoplasmic autoantibodies

What is it used for?

An ANCA test can help diagnose:

• Certain types of vasculitis, a condition that causes inflammation and swelling in your blood vessels. When this happens, your blood vessels narrow or close off. Over time, inflammation can also damage your organs and cause aneurysms (when your blood vessel walls are weakened). This test can show whether you have one or both types of ANCA, which can help your provider diagnose the correct type of vasculitis. It can also be used to help monitor treatment for the condition.
• Ulcerative colitis, a type of inflammatory bowel disease (IBD) that causes swelling and irritation in the lining of your colon (the largest part of your large intestine). If you have symptoms of IBD, your provider may use ANCA tests to see if your symptoms are being caused by ulcerative colitis or Crohn's disease. These two conditions can be difficult to tell apart. But an ANCA test can help with the diagnosis because ANCAs are more commonly found in ulcerative colitis.

There are several types of vasculitis associated with ANCA. Each type can cause serious health problems depending on which blood vessels it affects. These types include:

• Granulomatosis with polyangiitis (GPA). This condition used to be called Wegener's disease. It most often affects blood vessels in the lungs and sinuses. It may also affect the nose, windpipe (trachea), or kidneys.
• Microscopic polyangiitis (MPA). This disorder can affect several parts of the body, including the lungs, kidneys, nerves, skin, and joints.
• Eosinophilic granulomatosis with polyangiitis (EGPA). This condition used to be called Churg Strauss syndrome. It usually affects blood vessels in the lungs and sinuses. It may also affect the stomach and intestines, skin, heart, and nervous system. It often causes asthma and a high level of white blood cells called eosinophils.

Why do I need an ANCA test?

You may need an ANCA test if you:

• Have symptoms of vasculitis
• Are being treated for vasculitis
• Have symptoms of IBD

General symptoms of vasculitis may include:

• Fatigue
• Fever
• General aches and pains
• Loss of appetite
• Weight loss

These symptoms can develop over time or come on suddenly. Other symptoms depend on which type of vasculitis you have and which parts of your body are affected. Symptoms in some commonly affected areas include:

• Eyes, ears, and nose
  • Changes in vision or loss of vision
  • Red and/or itching, burning eyes
  • Ringing in the ears (tinnitus)
  • Hearing loss
  • Dizziness
  • Sinus infections
• Skin
  • Rashes or hives
  • Itching
  • Bruises
• Lungs
  • Coughing up blood
  • Shortness of breath
• Kidneys
  • Blood in the urine (pee)
  • Foamy urine, which is caused by protein in the urine
• Nervous system
  • Numbness, tingling, and/or weakness in different parts of the body
  • Shooting pains in the arms and legs
• Stomach and intestines
  • Open sores in the mouth
  • Diarrhea
  • Vomiting blood

Symptoms of inflammatory bowel disease (IBD) may include:

• Abdominal (belly) pain
• Diarrhea
• Weight loss
• Blood in stool (poop)
• Fever

What happens during an ANCA 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?

You usually don't need any special preparations for an ANCA test. But ANCA testing may be done with other blood tests. Your provider will let you know if you need to do anything to prepare.

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 provider will consider the results of your ANCA test along with your symptoms and the results of other tests. Ask your provider to explain what your test results mean.

If you were tested for vasculitis:

• A negative result means that no ANCAs were found in your blood sample. Your symptoms probably aren't caused by vasculitis.
• A positive result means that ANCAs were found in your blood sample. This may mean you have vasculitis. Your test results will also show which type of ANCAs were found. This can help diagnose the type of vasculitis you have.

If ANCA antibodies are found, another test may be done on your blood sample to see how much ANCA is in your blood. You will often need other blood tests and a biopsy to confirm the diagnosis. A biopsy is a procedure that removes a small sample of tissue or cells for testing. The tissue sample will be taken from a swollen blood vessel.

If you were tested to monitor treatment for vasculitis, ANCA test results may show whether your treatment is working.

If you were tested for inflammatory bowel disease (IBD), your provider will consider your ANCA test results along with the results from another antibody blood test. This test checks for an antibody called ASCA (anti-Saccharomyces cerevisiae antibodies). ASCAs are common in people with IBD. You may have:

• Ulcerative colitis if ANCA was found, but ASCA was not found.
• Crohn's disease if ANCA was not found, but ASCA was found.

If neither antibody was found, you may still have IBD.

If you have questions about your results, talk with your provider.

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