ANCA Test

How does an ANCA test work?

At the lab, some of your blood sample is mixed with neutrophils on a slide. If the sample contains ANCAs, they will attach to the neutrophils. A special stain added to the slide helps the lab see this activity under a microscope. The cells have a certain pattern of fluorescence, which the lab classifies as cytoplasmic (cANCA) or perinuclear (pANCA).

A laboratory may use one or two types of ANCA testing:

• Indirect immunofluorescence (IIF): This type of testing gives a positive or negative result, meaning you have the autoantibodies or you don’t.
• Enzyme-linked immunosorbent assay (ELISA): This type of test helps to identify targeted protein in the neutrophils.

How do I prepare for an ANCA test?

ANCA testing doesn’t usually require any preparation.

Sometimes a blood test measures several things at once. Some tests require you to fast for eight to 12 hours. That means you shouldn’t eat or drink anything besides water. Your healthcare provider will give you specific instructions.

What should I expect during an ANCA test?

Collecting blood for the ANCA test takes only a few minutes. In an office, clinic or lab, a healthcare provider will:

• Wrap a band tightly around your upper arm.
• Clean an area of skin.
• Insert a needle into a vein inside the elbow area, which may cause a stinging or pinching feeling.
• Attach a tube to the needle and fill the tube with blood.
• Remove the band and needle, then put pressure on the puncture wound to help stop any bleeding.
• Place a bandage on the skin.

What can I expect after an ANCA test?

Your healthcare provider may ask you to keep the bandage on for a few hours. You may also need to avoid exercise for a few hours after the blood test.

What are the risks of an ANCA test?

Blood tests are very safe and involve little risk. You may have a small bruise where the needle went into your skin. Rarely, the vein may swell. Warm compresses can help.

When should I know the results of an ANCA test?

ANCA testing is performed at a special laboratory. Results may take several days to a week.

What do ANCA test results mean?

Your healthcare provider will talk to you about the test results and what they mean for you. If the results are negative, then you likely don’t have autoimmune vasculitis. If the results are positive, you may be diagnosed with autoimmune vasculitis.

Your healthcare provider may order additional tests, such as a biopsy or more bloodwork. And they’ll consider many other factors to make an accurate diagnosis.