c-ANCA Blood Test (Antineutrophil Cytoplasmic Antibody)
Antibody test to help diagnose vasculitis, a condition causing inflamed blood vessels.
The c-ANCA blood test detects cytoplasmic antineutrophil cytoplasmic antibodies, a distinct class of autoantibodies directed against components of neutrophil cytoplasm, most commonly proteinase 3 (PR3). It is used primarily to support the investigation of small vessel vasculitides, particularly granulomatosis with polyangiitis (GPA, formerly Wegener's granulomatosis), and to help differentiate these conditions from other inflammatory or infective disorders. The test is typically requested for patients presenting with unexplained systemic inflammation, recurrent sinus or respiratory symptoms, renal impairment, or other features suggestive of an ANCA-associated vasculitis. Testing may also be used to monitor disease activity and treatment response in patients with a known diagnosis.
The assay is performed on a simple blood sample using an immunoassay method, with positive results often confirmed by enzyme-linked immunosorbent assay (ELISA) or similar techniques to identify the specific target antigen, such as PR3. This targeted approach improves diagnostic accuracy and helps distinguish c-ANCA from p-ANCA (perinuclear pattern), which is more commonly associated with microscopic polyangiitis and other conditions.
Biomarkers included
Autoantibodies
- c-ANCA (cytoplasmic antineutrophil cytoplasmic antibody)
Why it matters
Identifying c-ANCA, particularly when directed against proteinase 3, provides a highly specific clue in the diagnostic pathway for ANCA-associated vasculitis. Early recognition supports timely referral to rheumatology or renal services, enables appropriate immunosuppressive treatment, and helps reduce the risk of irreversible organ damage. For patients already diagnosed, serial testing can offer valuable insight into disease activity and guide therapeutic decisions.
Autoantibodies
- c-ANCA (cytoplasmic antineutrophil cytoplasmic antibody)
No special preparation required.
For blood tests, we recommend drinking plenty of water beforehand to ensure smooth sample collection. If you are taking any regular medication, continue to do so unless advised otherwise by your doctor.
Important Clinical Information:
This test is a screening tool to monitor and support your overall health. It does not replace your GP or Consultant.
Always discuss your test results, especially any abnormal results, with your GP, who can interpret them in the context of your medical history and overall health.