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Blood Test Tracker

ANCA Screen (IFA)

Checks for antibodies that target neutrophils, a type of white blood cell. A positive result is linked to some forms of blood vessel inflammation and leads to more specific tests.

AI-verified against cited sources. Awaiting expert reviewAlso called ANCA, ANCA IFALOINC 17351-8

What it is

ANCA stands for anti-neutrophil cytoplasmic antibodies. Neutrophils are white blood cells that help fight infection. In the immunofluorescence version of this test, a lab places your serum on slides of neutrophils and looks for a glow under a microscope. The result is reported as negative or positive. If it is positive, the lab often reports the pattern, called c-ANCA (cytoplasmic), p-ANCA (perinuclear) or atypical, along with a titer. It may also test for the two main targets, PR3 and MPO.

Why it matters

A positive ANCA is one clue clinicians use when they look for ANCA-associated vasculitis, a group of conditions in which small blood vessels become inflamed. These include granulomatosis with polyangiitis, microscopic polyangiitis and eosinophilic granulomatosis with polyangiitis. ANCA is also found in some people with ulcerative colitis, other bowel and liver conditions, and other autoimmune conditions. So the screen is read together with the pattern, the MPO and PR3 results, your symptoms and sometimes a biopsy. Many labs now start with MPO and PR3 blood tests instead, and a 2017 international consensus said those tests can be the first step when vasculitis is suspected. You may therefore not see this screen on every report.

If it’s high

A positive screen means antibodies were seen on the neutrophil slide. It does not say which condition, if any, is behind it. Your clinician will look at the pattern, the MPO and PR3 results and your symptoms, and may order more blood tests, urine tests, scans or a biopsy to learn more.

Common causes

  • Inflammatory bowel disease, especially ulcerative colitis
  • Liver conditions such as primary sclerosing cholangitis and autoimmune hepatitis
  • Other autoimmune conditions, including lupus and drug-induced lupus
  • ANCA-associated vasculitis (granulomatosis with polyangiitis, microscopic polyangiitis, eosinophilic granulomatosis with polyangiitis)

What can help

  • Ask which pattern was seen and whether MPO and PR3 tests were done
  • Ask whether kidney and urine tests are needed
  • Share a full list of your medicines with your clinician

What can affect your result

  • Test method: the immunofluorescence slide is read by eye, and studies found large differences between methods
  • Pattern and target: about 90% of people with a p-ANCA pattern have MPO antibodies and about 85% of people with a c-ANCA pattern have PR3 antibodies (ARUP)
  • Underlying condition: bowel, liver and other autoimmune conditions can give a positive result
  • Lab approach: some labs start with MPO and PR3 tests and use the immunofluorescence screen only as a follow-up
  • The slide is read by eye. A European study of 251 people with ANCA-associated vasculitis found large differences between two immunofluorescence methods (EUVAS 2017).
  • Samples that are grossly hemolyzed or very lipemic may be rejected (Quest).
  • Titers and cutoffs differ between labs, so results from different labs are not directly comparable.

The result reflects your blood on the day of the draw.

When to talk to a clinician

A positive screen is not an emergency by itself, but vasculitis can affect the lungs and kidneys. Contact a clinician promptly if you cough up blood, have new shortness of breath, see blood or foam in your urine, or have new numbness or weakness. Call your local emergency number for severe trouble breathing or heavy bleeding.

Questions you could ask

  • Does my lab use the immunofluorescence screen, MPO and PR3 tests, or both?
  • Which pattern was seen, and were MPO and PR3 tested?
  • Do I need kidney, urine or lung tests?
  • Should I see a specialist, such as a rheumatologist or a kidney specialist?
  • If my symptoms continue, would other tests or a repeat be useful?

Questions people ask

My ANCA screen is positive. Does that mean I have vasculitis?

Not necessarily. ANCA can also be found in conditions such as ulcerative colitis and some liver and autoimmune conditions. Your clinician will look at the pattern, MPO and PR3 results, your symptoms and often kidney or urine tests. A biopsy is often needed to confirm vasculitis.

What are c-ANCA and p-ANCA?

They are the two main glow patterns. In c-ANCA the glow is spread through the cell fluid. In p-ANCA it is around the center of the cell. Most c-ANCA patterns are linked to PR3 antibodies and most p-ANCA patterns to MPO antibodies.

Why does my report show MPO and PR3 results but no ANCA screen?

Many labs now start with MPO and PR3 blood tests. A 2017 international consensus said these tests can be the first step when vasculitis is suspected. Some labs then run the immunofluorescence screen as a follow-up when needed.

Show the science and sources

For clinicians and researchers

ANCA are detected by indirect immunofluorescence on neutrophils, which shows a cytoplasmic (c-ANCA), perinuclear (p-ANCA) or atypical pattern. ARUP runs ethanol- and formalin-fixed slides side by side to separate p-ANCA from other nuclear staining. About 85% of c-ANCA patterns are directed at proteinase 3 (PR3) and about 90% of p-ANCA patterns at myeloperoxidase (MPO) (ARUP). The 1999 international consensus called for immunofluorescence screening followed by PR3 and MPO immunoassays. The revised 2017 international consensus proposed that high-quality PR3 and MPO immunoassays can be the primary screen for suspected granulomatosis with polyangiitis and microscopic polyangiitis, without the categorical need for immunofluorescence. In a multicentre European study, the area under the curve for separating ANCA-associated vasculitis from controls was 0.923 and 0.843 for two immunofluorescence methods and 0.936 to 0.959 for most antigen-specific immunoassays, and testing each sample by both methods was not necessary for maximal accuracy (EUVAS multicentre study, 2017). In bowel disease, ANCA can show a p-ANCA or c-ANCA pattern, and these antibodies may not be directed at MPO (Quest). Mayo includes an immunofluorescence ANCA result in its IBD serology panel (negative when not detectable). Quest lists immunoassay as the method for its ANCA screen and reports it as negative or positive, with a reflex titer for c-ANCA, p-ANCA and atypical p-ANCA, each negative below 1:20. ARUP reports pattern (none detected) and titer (below 1:20) in its vasculitis profile. The ANCA screen result code listed for the Quest test is 17351-8, and Mayo lists 17355-9 for its IBD ANCA result.

LOINC 17351-8 (primary), 35279-9, 17355-9. Specimen: serum.

Sources

  1. ANCA Screen with Reflex to ANCA Titer (test code 70171), Quest Diagnostics
  2. ANCA-Associated Vasculitis Profile (ANCA/MPO/PR3) (test 3003745), ARUP Laboratories
  3. MPO/PR3 (ANCA) Antibodies (test 0050707), ARUP Laboratories
  4. Cytoplasmic Neutrophil Antibodies, Inflammatory Bowel Disease Panel, Serum (test ANCA2), Mayo Clinic Laboratories
  5. Position paper: Revised 2017 international consensus on testing of ANCAs in granulomatosis with polyangiitis and microscopic polyangiitis, Nature Reviews Rheumatology (2017)
  6. Detection of antineutrophil cytoplasmic antibodies (ANCAs): a multicentre European Vasculitis Study Group (EUVAS) evaluation of the value of indirect immunofluorescence (IIF) versus antigen-specific immunoassays, Annals of the Rheumatic Diseases (2017)
  7. Antineutrophil Cytoplasmic Antibodies (ANCA) Test, MedlinePlus, National Library of Medicine
  8. LOINC codes verified with the NLM Clinical Tables LOINC search (e.g. 35279-9), U.S. National Library of Medicine

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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