At a Glance
Why Get Tested?
To test for certain autoimmune disorders, such as Wegener's granulomatosis (WG) now termed Granulomatosis with Polyangitis (GPA), microscopic polyangitis (MPA), and a number of others.
When to Get Tested?
When your doctor thinks that you have symptoms that may be due to a vascular autoimmune disorder; sometimes to monitor response to therapy.
A blood sample drawn from a vein in your arm.
Test Preparation Needed?
The Test Sample
What is being tested?
Antineutrophil cytoplasmic antibodies (ANCA) are a group of autoantibodies produced when a person's immune system mistakenly targets its own neutrophil proteins. Two of the most commonly targeted proteins are myeloperoxidase (MPO) and proteinase 3 (PR3). This results in the production of antibodies to MPO and/or PR3. The ANCA blood test detects the presence or absence of these autoantibodies by looking at the pattern of fluorescence on a slide under the microscope.
Antineutrophil cytoplasmic antibodies may be present in a variety of autoimmune disorders that cause inflammation and damage to blood vessels throughout the body (systemic vasculitis). Vasculitis can cause tissue and organ damage due to the narrowing and obstruction of blood vessels and the subsequent loss of blood supply. It can also produce areas of weakness in blood vessel walls, known as aneurysms, which have the potential to rupture.
The symptoms experienced by a person with systemic vasculitis depend upon the degree of autoimmune activity and the parts of the body involved. Early in the disease process, symptoms are often nonspecific – they include fatigue, fever, weight loss, muscle aches, and night sweats. As the disorder progresses, vascular damage may affect the functioning of the kidneys, eyes, skin, lungs, and liver. This can cause a wide range of symptoms related to these organ systems.
PR3 antibodies are most frequently seen in Wegener's granulomatosis (WG). MPO antibodies are most often associated with microscopic polyangiitis but may also be seen in people with pauci-immune necrotizing glomerulonephritis, Churg-Strauss syndrome, and WG. For more about these conditions, visit the Vasculitis Foundation. These antibodies may also occur in ulcerative colitis and in bacterial endocarditis.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
Ask a Laboratory Scientist
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.