What is an antineutrophil cytoplasmic antibodies (ANCA) test?

This 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. But sometimes antibodies attack the healthy cells of your own tissues and organs by mistake. This is called autoimmune disease.

ANCAs attack healthy white blood cells called neutrophils. This can lead to a disorder called autoimmune vasculitis. There are several types of autoimmune vasculitis, but they all cause inflammation and swelling in your blood vessels. When this happens, your blood vessels can narrow or close off. This can cause different types of serious health problems depending on which blood vessels in your body are affected.

There are two main kinds of ANCA called pANCA and cANCA. Each type targets a specific protein inside white blood cells. An ANCA test can show whether you have one or both types of antibodies. This information helps your health care provider diagnose which type of autoimmune vasculitis you have so you can get the right treatment.

Testing for pANCA can also help diagnose certain types of inflammatory bowel disease (IBD). IBD is a group of chronic (long-lasting) autoimmune diseases that cause swelling and irritation in your stomach and intestines.

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

What is it used for?

ANCA testing is used to help:

• Find out if you have autoimmune vasculitis and which type.
• Monitor treatment for autoimmune vasculitis.
• Diagnose whether you have ulcerative colitis or Crohn's disease. Both conditions are types of inflammatory bowel disease. ANCAs are more commonly found in ulcerative colitis.

Types of autoimmune vasculitis include:

• Granulomatosis with polyangiitis (GPA). This condition used to be called Wegener's disease. It most often affects blood vessels in the lungs and/or sinuses. It may also affect the nose, windpipe, 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/or 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?

If you have symptoms of autoimmune vasculitis, you may need an ANCA test. Symptoms may develop slowly or quickly. They may be mild or severe.

General symptoms may include:

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

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

You may also need an ANCA test if you have symptoms of inflammatory bowel disease (IBD), which 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 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 autoimmune vasculitis:

• A negative result means that no ANCAs were found in your blood sample. Your symptoms probably aren't caused by autoimmune vasculitis.
• A positive result means that ANCAs were found in your blood sample. This may mean you have autoimmune 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 blood vessel that is swollen.

If you were tested to monitor treatment for autoimmune vasculitis, ANCA test results may show whether your treatment is working. But this test isn't always an accurate way to measure how much disease you have.

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). ASCA 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.