Blood test
ANCA Test
An ANCA test looks for antibodies linked to certain types of blood vessel inflammation (vasculitis).
Quick answer
ANCA Test: what it is and what the results mean
The ANCA (antineutrophil cytoplasmic antibody) test detects antibodies that target white blood cells called neutrophils. It is associated with a group of autoimmune conditions that inflame small blood vessels.
- Why it is done: It is used to help diagnose types of small-vessel vasculitis such as granulomatosis with polyangiitis and microscopic polyangiitis, in people with symptoms like unexplained kidney problems, lung bleeding, sinus disease, rashes or nerve problems.
- Understanding results: A positive ANCA supports a diagnosis of vasculitis in the right clinical setting and may be reported by pattern (c-ANCA or p-ANCA) and specific antigen.
What it is
The ANCA (antineutrophil cytoplasmic antibody) test detects antibodies that target white blood cells called neutrophils. It is associated with a group of autoimmune conditions that inflame small blood vessels.
Why it is done
It is used to help diagnose types of small-vessel vasculitis such as granulomatosis with polyangiitis and microscopic polyangiitis, in people with symptoms like unexplained kidney problems, lung bleeding, sinus disease, rashes or nerve problems.
What to expect
It is a standard blood test from a vein in the arm. It is often part of a wider panel of tests when vasculitis is suspected, and results usually take several days.
Understanding the results
A positive ANCA supports a diagnosis of vasculitis in the right clinical setting and may be reported by pattern (c-ANCA or p-ANCA) and specific antigen. Results are always interpreted with symptoms, other blood tests and sometimes a biopsy.
Good to know
Risks and limitations
It is a safe blood test. A positive result is not specific on its own and a negative result does not fully exclude vasculitis, so diagnosis relies on the whole clinical picture.
Education and reference only. This explains the test in general terms and is not medical advice. Always follow the specific instructions from the team arranging your test, and discuss your results with your clinician.
Answers
ANCA Test: frequently asked questions
What conditions is the ANCA test used for?
It is mainly used to help diagnose ANCA-associated vasculitis — a group of conditions that inflame small blood vessels and can affect the kidneys, lungs, sinuses, nerves and skin.
Is a positive ANCA always serious?
A positive result in someone with suggestive symptoms points to vasculitis, which needs prompt specialist care. However, it must be interpreted carefully, as false positives can occur.
Related tests
Other blood test investigations
Sources
Where this is drawn from
- NHS — Tests and treatments
- NICE — diagnostic guidance
- Association for Laboratory Medicine / relevant professional body
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