Description: An ANCA screen is used to detect antineutrophil cytoplasmic antibodies in your blood to test for autoimmune vasculitis and to differentiate between Crohn’s disease and ulcerative colitis when testing for inflammatory bowel disease.
Also Known As: ANCA test, cANCA test, pANCA test, Serine Protease 3 test, Acticytoplasmic Test, 3-ANCA test, PR3-ANCA Test, MPO-ANCA test
Collection Method: Blood Draw
Specimen Type: Serum
Test Preparation: No preparation required
When is an ANCA Screen test ordered?
When a person exhibits symptoms and signs that point to systemic autoimmune vasculitis, an ANCA test must be performed. Early indications of the illness could include a fever, weariness, weight loss, aches in the muscles and/or joints, and nocturnal sweats. As the illness worsens, damage to blood arteries all throughout the body may result in the signs and symptoms of consequences affecting different tissues and organs.
When a patient exhibits symptoms that point to inflammatory bowel disease and the doctor wants to differentiate between Crohn's disease and ulcerative colitis, they may be prescribed an ANCA test together with an anti-Saccharomyces cerevisiae antibody test.
What does an ANCA Screen test check for?
The immune system of a person makes autoantibodies called antineutrophil cytoplasmic antibodies that wrongly target and attack proteins found in the person's neutrophils. These autoantibodies are found in the blood and their concentration is determined by ANCA testing. The autoantibodies that target the proteins myeloperoxidase and proteinase 3 are two of the most prevalent forms or subgroups of ANCA.
An individual's blood sample is combined with neutrophils for the test, which is then put on a slide and stained fluorescently. Under a microscope, ANCA will exhibit a pattern of fluorescence if they are present. Atypical ANCA, perinuclear, or cytoplasmic ANCA are possible classifications for the pattern. Alternately, a direct ELISA assay can be used in the laboratory to check for myeloperoxidase or proteinase 3 antibodies. When investigating possible vasculitis cases, fluorescence and ELISA testing are frequently combined.
ANCA may be found in a number of autoimmune conditions that result in organ failure, tissue damage, and inflammation.
Systemic vasculitis is a group of diseases characterized by blood vessel deterioration and injury. Due to blood channel narrowing and obstruction, which results in a reduction in blood supply, it can harm tissue and organs. Aneurysms, which are weak spots in the walls of blood vessels that have the potential to burst, can also be created. The degree of autoimmune activity and the areas of the body affected by systemic vasculitis determine the symptoms that an affected person may experience. There are a few forms of systemic vasculitis that are closely linked to ANCA production:
- Polyangiitis and granulomatosis
- Miniature polyangiitis
- Polyangiitis along with eosinophilic granulomatosis
- Nodular polyarteritis
The most typical cases of cANCA/PR3 antibodies and pANCA/MPO antibodies include granulomatosis with polyangiitis and microscopic polyangiitis, respectively. To varied degrees of responsiveness, both may be present in all three categories.
An instance of inflammatory bowel disease known as ulcerative colitis is characterized by inflamed and harmed tissues in the colon's lining. UC and Crohn disease, another kind of IBD that can affect any section of the intestinal tract, can be challenging to distinguish from one another. Atypical ANCA is typically seen in UC patients, but only 20% of CD patients may be positive.
Lab tests often ordered with an ANCA Screen test:
- Antibody Panel
- Complete Blood Count (CBC)
- Sed Rate
- C-Reactive Protein
Conditions where an ANCA Screen test is recommended:
- Autoimmune Disorders
- Inflammatory Bowel Disease
How does my health care provider use an ANCA Screen test?
ANCA antibody tests can be used to:
- Assist in the detection and diagnosis of granulomatosis with polyangiitis, microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis, among other types of autoimmune vasculitis. This test may occasionally be performed to keep tabs on the patient's progress in therapy or to spot a relapse of certain illnesses.
- Help distinguish between Crohn's disease and ulcerative colitis, two prevalent varieties of inflammatory bowel illness.
ANCA are immune system-generated autoantibodies that wrongly target proteins in a person's neutrophils. Myeloperoxidase and proteinase 3 are the targets of the majority of ANCA subgroups.
There are two possible exam types:
- ANCA testing are most frequently carried out with indirect immunofluorescence microscopy. Neutrophils and serum samples are combined to allow any potential autoantibodies to interact with the cells. A fluorescent stain is applied to the sample before it is placed on a slide. After that, the slide is studied under a microscope to identify any patterns. MPO antibodies are linked to the perinuclear pattern, while PR3 antibodies are linked to the cytoplasmic pattern. Atypical ANCA is yet another potential pattern.
- Antibodies to proteinase 3 and myeloperoxidase can be evaluated separately and specifically using an immunoassay technique.
ANCA, MPO, and PR3 are three tests that some labs will run as a panel, while others will only run MPO and PR3 if the initial ANCA test is positive.
Erythrocyte sedimentation rate and/or C-reactive protein tests to check for inflammation, complete blood counts to measure and assess white and red blood cells, and urinalysis, blood urea nitrogen, and creatinine tests to assess kidney function are additional tests that may be carried out to help with diagnosis. Viral tests for hepatitis or CMV may be prescribed for some patients.
What do my ANCA Screen test results mean?
Care must be taken while interpreting ANCA test results and many considerations must be made. A doctor will take into account clinical symptoms in addition to the outcomes of laboratory testing and other kinds of examinations, such imaging investigations.
Positive results from the ANCA, PR3, and/or MPO tests aid in confirming the diagnosis of systemic autoimmune vasculitis and identifying its many subtypes. However, a biopsy of an afflicted spot is frequently needed to confirm a diagnosis.
Results from negative ANCA tests indicate that an autoimmune vasculitis is not likely to be the cause of a person's symptoms.
Multiple ANCA patterns may be observed for a successful outcome using the indirect immunofluorescence microscopy method.
Perinuclear fluorescence is especially prominent close to the nucleus. In about 90% of samples MPO antibodies will be present with a pANCA pattern.
Fluorescence that is cytoplasmic spreads throughout the cell's cytoplasm. In about 85% of samples PR3 antibodies will be present with a cANCA pattern.
Very little or no fluorescence indicates negative ANCA.
If the ANCA test is positive, another test is run to figure out how much antibody is actually present. The term for this is titer. A serum sample is diluted in stages to determine the titer, and the presence of the antibody is checked after each dilution. The titer is the highest dilution at which the antibody can be found. The titer is 1:64, for instance, if a serum tests positive after being diluted 64 times. More antibody is found in the blood the greater the titer.
ANCA levels can fluctuate over time and are occasionally used in a broad sense to monitor disease activity and/or therapeutic response; nevertheless, titer levels may be variable in certain patients, inadequately reflecting the status of remission or relapse.
More than 80% of individuals with active granulomatosis with polyangiitis have a positive PR3 antibody test and a positive cANCA or pANCA.
Indicators of microscopic polyangitis, glomerulonephritis, eosinophilic granulomatosis with polyangiitis, and Goodpasture syndrome include positive tests for MPO antibodies and a positive pANCA. Other autoimmune diseases such systemic lupus erythematosus, rheumatoid arthritis, and Sjögren syndrome may also exhibit MPO and pANCA.
Patients with signs of an inflammatory bowel illness may benefit from ANCA testing.
If the atypical ANCA is positive and the ASCA is negative, ulcerative colitis is probably present.
As long as ASCA is positive and atypical ANCA is negative, Crohn's disease is most likely present. Even if ANCA and/or ASCA tests are negative, a person may nonetheless have UC, CD, or another IBD.
We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.