The essentials

ANCA are antibodies against proteins inside neutrophils, a type of white blood cell. Labs report a pattern (c-ANCA or p-ANCA) and, more and more, two measured antibodies: PR3 and MPO. A positive result supports, but never proves alone, a small-vessel vasculitis; it is also seen with ulcerative colitis, liver disease, infections and some drugs. Blood in the urine, a rising creatinine or coughing up blood with a positive ANCA needs to be seen quickly.

How do I read my ANCA test result?

An ANCA report can have four parts: a screen, a pattern, a titer and two antibody levels[2][3]. Here is a fictitious US example.

Fictitious example of ANCA report lines (United States format)
TestResultReference rangeFlag
ANCA Screen, IFAPositiveNegativeA
ANCA PatternP-ANCANone detectedA
ANCA Titer1:320<1:20H
Myeloperoxidase Ab (MPO)68 U/mL<20 U/mLH
Proteinase-3 Ab (PR3)<2 U/mL<20 U/mL-
  1. Screen, IFA: your serum is put on neutrophils fixed on a slide and read under a fluorescence microscope[2].
  2. Pattern: P-ANCA means the glow is around the nucleus; C-ANCA means it fills the cytoplasm; "atypical" fits neither[2].
  3. Titer: the highest dilution of your serum that still glows. A US reference lab reports less than 1:20 as normal[4].
  4. MPO and PR3: measured by immunoassay, the line that matters most for vasculitis[6]. The unit (U/mL, IU/mL or an index) and the cut-off depend on the kit, so only compare with the range printed next to your result. Here MPO is positive, the usual match for a P-ANCA[2].

A P-ANCA with an MPO line, or a "positive" without a number? BloodSense explains each line of your report next to your kidney and inflammation results, and helps you list questions for your doctor.

Get my ANCA result explained

What is an ANCA test used for?

The main use is to help diagnose ANCA-associated vasculitis, an inflammation of small blood vessels, and sometimes to follow it during treatment[1]. It is ordered for symptoms such as fever, weight loss, sinus problems, rashes, coughing up blood, numbness, or blood or protein in the urine[1]. The upper and lower airways and the kidneys are the organs most often and most severely affected[8].

The three diseases are granulomatosis with polyangiitis (GPA, formerly Wegener's), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg-Strauss)[1]. Many experts suggest grouping them by antibody, as PR3-positive or MPO-positive disease, and EGPA as ANCA-positive or ANCA-negative[8]. European guidelines recommend ANCA testing together with biopsies to establish the diagnosis[9].

A second use is in bowel disease: with the ASCA antibody, ANCA can help tell ulcerative colitis from Crohn's disease when the diagnosis is unclear[1][7].

c-ANCA vs p-ANCA, PR3 vs MPO: what is the difference?

c-ANCA and p-ANCA describe what the lab sees under the microscope. PR3 and MPO name the protein the antibody actually targets. In 2017 an international consensus concluded that high-quality PR3 and MPO immunoassays can be the first screening test for suspected GPA and MPA, without the need for immunofluorescence[6]. So some reports show only PR3 and MPO, with no pattern.

ANCA patterns, target antibodies and usual associations
Pattern (IFA)Usual target (immunoassay)Most often linked to
c-ANCA (cytoplasmic)PR3 in about 85%[2]Granulomatosis with polyangiitis[2]
p-ANCA (perinuclear)MPO in about 90%[2]Microscopic polyangiitis; also EGPA[2]
Atypical p-ANCA or atypical ANCATargets not yet well defined[7]Ulcerative colitis, autoimmune liver disease[2][7]

The pattern can mislead: antinuclear antibodies can make the slide look ANCA-positive. Some labs therefore run an ANA blood test automatically after a positive ANCA, to rule out this false positive[3].

What is the normal range for an ANCA test?

Normal is negative: no pattern, a titer below the lab's cut-off and PR3 and MPO below their limits. Numbers differ between labs:

ANCA reference values from different laboratories
TestNormal (negative)Source
ANCA screen by IFANegativeLabcorp (United States)[3]
ANCA IFA titerLess than 1:20, pattern none detectedARUP Laboratories (United States)[4]
MPO antibodies (FEIA)Below 3.5 IU/mL; 3.5 to 5 equivocal; above 5 positiveNiguarda hospital laboratory (Italy)[5]
PR3 antibodies (FEIA)Below 2; 2 to 3 equivocal; above 3 positiveNiguarda hospital laboratory (Italy)[5]

The same number can be negative with one kit and positive with another: your laboratory's range applies.

What causes a positive ANCA?

  • Common Inflammatory bowel disease: ANCA, usually an atypical p-ANCA, is more common in ulcerative colitis than in Crohn's disease[1][2].
  • Possible Other autoimmune conditions: rheumatoid arthritis, lupus and Sjögren's disease can carry a p-ANCA or MPO antibodies without vasculitis[2].
  • Possible ANCA-associated vasculitis (GPA, MPA, EGPA). ANCA is found in about 90% of people with GPA[2].
  • Possible Autoimmune liver disease, such as autoimmune hepatitis or primary sclerosing cholangitis[2][7].
  • Possible Infections, including lung infections and infection of the heart valves (endocarditis). ANCA develops in about 10% of people with endocarditis[2][10].
  • Possible Medicines: in one US series of 30 patients with very high MPO antibodies, 33% had taken hydralazine (a blood pressure drug) and 10% propylthiouracil (a thyroid drug)[11]. Never stop a medicine on your own.
  • Possible Cocaine cut with levamisole: levamisole, a deworming drug, was found in an estimated 71% of US cocaine samples. It can cause an ANCA vasculitis with skin, kidney and lung damage[12].
  • Rare Anti-GBM disease, a kidney and lung disease in which experts advise testing for PR3 and MPO antibodies as well[7].

Can you have a positive ANCA without vasculitis?

Yes. Without symptoms of vasculitis, the 2020 international consensus does not recommend routine ANCA testing in most of the conditions listed above[7]. In the right clinical setting, PR3 and MPO antibodies are highly sensitive and specific; outside it, they can mislead[10]. The diagnosis rests on symptoms, urine and kidney tests, imaging and often a biopsy[1][9].

Alongside ANCA, your doctor will usually look at creatinine and eGFR, a urinalysis, the sedimentation rate (ESR), C-reactive protein and a complete blood count[2]. If EGPA is suspected, the eosinophil count is checked too.

Do I need to fast before an ANCA test?

No special preparation is usually needed; fasting applies only if another test drawn at the same time requires it[1]. Before the draw, check this list:

  • Bring a full list of your medicines, including any taken in the past months, such as hydralazine or propylthiouracil[11].
  • Tell the doctor about any recreational drug use; it changes how the result is read[12].
  • Mention a recent infection or heart valve problem.
  • Bring earlier ANCA reports: only the same lab and method compare well.

Practical tips are in our guide to what to expect at a blood draw.

When is a positive ANCA urgent?

When to see a doctor

  • Emergency: call 911 if you cough up blood, are short of breath, or pass very little urine, whatever your ANCA result.
  • Within 24 to 48 hours if a positive PR3 or MPO comes with blood in the urine, protein in the urine, a creatinine higher than on your last test, new swelling of the legs, a spreading rash or numbness. Untreated, this disease has a poor outlook; treatment has greatly improved survival[8].
  • At your next appointment if you feel well and have an atypical p-ANCA with negative PR3 and MPO.

Questions to ask your doctor

  1. Was my result a pattern only, or were PR3 and MPO measured too?
  2. Do my urine test and creatinine show any kidney involvement?
  3. Could one of my medicines explain this result?
  4. Do I need a biopsy, and when should the test be repeated?

Frequently asked questions

Does a negative ANCA rule out vasculitis?

It makes an autoimmune vasculitis unlikely[2], but not impossible: EGPA in particular also exists in an ANCA-negative form[8].

Can ANCA levels predict a relapse?

Not reliably on their own. Levels go up and down, and the value of repeat testing is still debated; it may help most in people with kidney involvement or treated with rituximab[2][10].

Is ANCA the same as ANA?

No. ANA targets the cell nucleus and is used mainly for lupus and related diseases; ANCA targets the neutrophil cytoplasm. A positive ANA can, however, make an ANCA slide look falsely positive[3].

  1. MedlinePlus. Antineutrophil Cytoplasmic Antibodies (ANCA) Test. US National Library of Medicine. medlineplus.gov (accessed November 5, 2026)
  2. Testing.com. Antineutrophil Cytoplasmic Antibodies (ANCA, MPO, PR3). testing.com (accessed November 5, 2026)
  3. Labcorp. Anti-Neutrophil Cytoplasmic Ab (ANCA) by Indirect Immunofluorescence (IFA) (test 520090). labcorp.com (accessed November 5, 2026)
  4. ARUP Laboratories. Anti-Neutrophil Cytoplasmic Antibody, IgG by IFA (test 3003747). ltd.aruplab.com (accessed November 5, 2026)
  5. ASST Grande Ospedale Metropolitano Niguarda. p-ANCA and c-ANCA laboratory test sheets. ospedaleniguarda.it (accessed November 5, 2026)
  6. Bossuyt X, Cohen Tervaert JW, Arimura Y, et al. Position paper: Revised 2017 international consensus on testing of ANCAs in granulomatosis with polyangiitis and microscopic polyangiitis. Nat Rev Rheumatol. 2017;13(11):683-692. doi:10.1038/nrrheum.2017.140 (accessed November 5, 2026)
  7. Moiseev S, Cohen Tervaert JW, Arimura Y, et al. 2020 international consensus on ANCA testing beyond systemic vasculitis. Autoimmun Rev. 2020;19(9):102618. doi:10.1016/j.autrev.2020.102618 (accessed November 5, 2026)
  8. Kitching AR, Anders HJ, Basu N, et al. ANCA-associated vasculitis. Nat Rev Dis Primers. 2020;6(1):71. doi:10.1038/s41572-020-0204-y (accessed November 5, 2026)
  9. Hellmich B, Sanchez-Alamo B, Schirmer JH, et al. EULAR recommendations for the management of ANCA-associated vasculitis: 2022 update. Ann Rheum Dis. 2024;83(1):30-47. doi:10.1136/ard-2022-223764 (accessed November 5, 2026)
  10. Kallenberg CG. Usefulness of antineutrophil cytoplasmic autoantibodies in diagnosing and managing systemic vasculitis. Curr Opin Rheumatol. 2016;28(1):8-14. doi:10.1097/BOR.0000000000000233 (accessed November 5, 2026)
  11. Choi HK, Merkel PA, Walker AM, Niles JL. Drug-associated antineutrophil cytoplasmic antibody-positive vasculitis: prevalence among patients with high titers of antimyeloperoxidase antibodies. Arthritis Rheum. 2000;43(2):405-413. doi:10.1002/1529-0131(200002)43:2<405::AID-ANR22>3.0.CO;2-5 (accessed November 5, 2026)
  12. Jin Q, Kant S, Alhariri J, Geetha D. Levamisole adulterated cocaine associated ANCA vasculitis: review of literature and update on pathogenesis. J Community Hosp Intern Med Perspect. 2018;8(6):339-344. doi:10.1080/20009666.2018.1536242 (accessed November 5, 2026)

This page is general information. It does not replace the advice of a doctor, who interprets your results with your symptoms, history and examination.