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c-ANCA (cytoplasmic) Titer

A microscope test for antibodies that make a type of white blood cell glow in a cytoplasmic pattern. It is mostly linked to PR3 antibodies and to a vasculitis called GPA.

AI-verified against cited sources. Awaiting expert reviewAlso called c-ANCA, cANCALOINC 14277-8

What it is

Anti-neutrophil cytoplasmic antibodies (ANCA) are immune proteins that attach to substances inside neutrophils, a type of white blood cell. In the IFA test, a lab scientist looks at neutrophils on a slide under a microscope. A glow spread through the middle of the cell is called the cytoplasmic pattern, or c-ANCA. It is usually caused by antibodies to a protein called PR3. The result is reported as negative, or as a titer, which is how far your blood can be diluted and still glow.

Why it matters

A positive c-ANCA, or a positive PR3 antibody test, is a feature of granulomatosis with polyangiitis (GPA), a rare disease in which small blood vessels become inflamed. The 2022 ACR/EULAR classification criteria give it +5 points, the largest weight of any item. It is not a diagnosis by itself, and a negative result does not rule vasculitis out. Clinicians read it together with symptoms, kidney and urine tests, imaging and sometimes a tissue sample.

If it’s high

A positive result means antibodies that stain the cytoplasm of neutrophils were found. In the right clinical setting this supports GPA. The same glow can come from other antibodies, so labs usually confirm a positive IFA result with a PR3 antibody test. Positive results also occur in some people who do not have vasculitis.

Common causes

  • Antibodies other than PR3, including ANA, that give a similar glow
  • Other autoimmune or inflammatory conditions, including bowel conditions, that can cause ANCA without vasculitis
  • Granulomatosis with polyangiitis (GPA), the condition most linked to this pattern
  • Other ANCA-associated vasculitis, less often

What can help

  • Ask whether a PR3 and MPO antibody test should be done to confirm the result
  • Ask which other tests, such as kidney function, urine tests or imaging, make sense for your symptoms
  • Keep track of nose, sinus, ear, lung and urine changes and share them with your clinician

What can affect your result

  • Test type: IFA shows the glow pattern, while PR3 and MPO immunoassays find the exact target, and the two can disagree
  • Other antibodies, including ANA, can give a similar glow
  • Each lab's dilution series and cutoff, for example Mayo's negative below 1:4 and ARUP's below 1:20
  • Some labs only report c-ANCA or p-ANCA when the result is positive
  • Antibodies other than PR3, including ANA, can make a similar glow under the microscope. Labcorp runs an ANA test when an ANCA result is positive for this reason.
  • A positive or unclear glow without a PR3 or MPO antibody can point to an antibody of unknown target, so labs confirm IFA results with PR3 and MPO immunoassays.
  • Labs use different dilution series and cutoffs. Mayo Clinic Laboratories calls a titer below 1:4 negative, and ARUP calls a titer below 1:20 negative.
  • Gross hemolysis, lipemia, icterus and bacterial contamination can lead a lab to reject the sample (Labcorp).

Titers can change with treatment, but Mayo Clinic Laboratories suggests PR3 or MPO antibody tests, not the IFA titer, for tracking disease activity.

When to talk to a clinician

Talk with a clinician promptly about a bloody nose or crusting in the nose, sinus problems that will not clear, hearing loss, a cough that will not go away, or blood or foam in the urine. Get urgent care if you cough up blood or have severe trouble breathing.

Questions you could ask

  • Is the IFA or a PR3 antibody test better for following me over time?
  • Should a PR3 and MPO antibody test be done to confirm this?
  • Do my symptoms mean I should have kidney or urine tests?
  • Which specialist should I see next?

Questions people ask

What is the difference between c-ANCA and PR3-ANCA?

c-ANCA is the glow pattern seen under a microscope. PR3-ANCA is a blood test that finds the specific protein (PR3) the antibody attaches to. Most c-ANCA patterns come from PR3 antibodies, but not all, so labs often run both.

Does a negative c-ANCA mean I do not have vasculitis?

No. Mayo Clinic Laboratories notes that negative ANCA results do not exclude ANCA-associated vasculitis. Your clinician looks at symptoms and other tests too.

Why does my report say "ANCA negative" with no titer?

Some labs report a c-ANCA or p-ANCA result only when it is positive. Otherwise the report simply says ANCA negative.

Show the science and sources

For clinicians and researchers

c-ANCA by indirect immunofluorescence on ethanol-fixed neutrophils shows diffuse cytoplasmic staining, usually from antibodies to proteinase 3 (PR3). Perinuclear staining (p-ANCA) usually reflects myeloperoxidase (MPO) antibodies. The 1999 international consensus called for IFA on all new patients, followed by PR3 and MPO ELISAs on positive samples. The revised 2017 consensus (Bossuyt et al.) proposes that high-quality PR3 and MPO immunoassays can be the primary screen without a categorical need for IFA. Mayo advises that a positive IFA ordered on its own should be confirmed with PR3 and MPO solid-phase immunoassays, and that a positive or indeterminate IFA without a detectable PR3 or MPO antibody may reflect an antibody of unidentified specificity. ANA can cause false-positive ANCA patterns, and Labcorp's ANCA profile reports C-ANCA and P-ANCA only when positive (otherwise 'ANCA Negative'), runs ANA when ANCA is positive, and confirms p-ANCA on formalin-fixed slides. In the 2022 ACR/EULAR GPA criteria, c-ANCA or anti-PR3 positivity scores +5 and p-ANCA or anti-MPO positivity scores -1. Mayo's IFA reference is below 1:4 (negative), while ARUP's is below 1:20. For monitoring disease activity Mayo suggests PR3 or MPO antibody tests rather than the IFA.

LOINC 14277-8 (primary), 32708-0, 17353-4. Specimen: serum.

Sources

  1. Cytoplasmic Neutrophil Antibodies, Serum (test ANCA), Mayo Clinic Laboratories
  2. ANCA Profile (RDL) (test 520149), Labcorp
  3. Position paper: Revised 2017 international consensus on testing of ANCAs in granulomatosis with polyangiitis and microscopic polyangiitis, Nature Reviews Rheumatology (2017)
  4. International Consensus Statement on Testing and Reporting of Antineutrophil Cytoplasmic Antibodies (ANCA), American Journal of Clinical Pathology (1999)
  5. Addendum to the International Consensus Statement on testing and reporting of antineutrophil cytoplasmic antibodies, American Journal of Clinical Pathology (2003)
  6. 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for granulomatosis with polyangiitis, Annals of the Rheumatic Diseases (ACR/EULAR) (2022)
  7. Anti-Neutrophil Cytoplasmic Antibody, IgG by IFA (test 3003747), ARUP Laboratories
  8. LOINC codes and long common names verified with the NLM Clinical Tables LOINC search, 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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