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Ancaabseriaacnc

Published: August 9, 2026Updated: August 17, 2026

A blood test that checks for antibodies that may attack white blood cells, helping diagnose certain autoimmune diseases affecting blood vessels.

Quick summary

{"ANCA test helps diagnose autoimmune diseases like vasculitis","It requires a simple blood draw from a vein in your arm","Positive results may indicate conditions affecting blood vessels","Results are combined with clinical symptoms for diagnosis","The test uses immunoassay technique to detect specific antibodies"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
45151-8
Short code
ANCA-S
Synonyms
ANCA Ab Ser IA-aCnc
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or red-top tube
Units
N/A
Ref low
0
Ref high
1
Critical range
0.5 N/A – —
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Immunoassay (Enzyme-linked immunosorbent assay/ELISA)
CPT
86255
SNOMED
122572009
Specimen volume
1-2 mL of serum
Stability
Room temperature: 8 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
Hemolysis max
100
Lipemia max
100
Icterus max
50
TAT
24–72 hours
Order
routine

What is this test?

The Neutrophil Cytoplasmic Antibody (ANCA) test is a blood test that detects special proteins called antibodies in your blood. These antibodies (anti-neutrophil cytoplasmic antibodies) can sometimes mistakenly attack your own white blood cells called neutrophils. This test uses a method called immunoassay to measure the amount of these antibodies in your serum (the liquid part of your blood).

Why do I need this test?

Your healthcare provider may order this test if you have symptoms that suggest an autoimmune disorder, particularly conditions affecting your blood vessels (vasculitis). These symptoms may include fever, unexplained weight loss, fatigue, joint pain, skin rashes, or problems with your kidneys or lungs. The test helps your doctor determine if your symptoms are caused by your immune system attacking your own body.

How is the test performed?

A healthcare professional will draw a small sample of blood from a vein in your arm using a needle. The blood is collected into a tube and sent to a laboratory for analysis. The laboratory uses special tests (immunoassay) to detect and measure the ANCA antibodies in your blood sample. You may feel a brief pinch or sting when the needle is inserted, and you might have slight bruising afterward, but serious complications are rare.

How to prepare for the test?

Generally, no special preparation is needed for the ANCA test. You can eat and drink normally before the test. However, always follow any specific instructions your healthcare provider gives you. Tell your doctor about all medications you are taking, as some medicines may affect test results. The test can be done at any time of day and does not require fasting.

Reference range

Negative: <1.0 AI (antibody index) or as defined by the performing laboratory; Positive: ≥1.0 AI suggests presence of neutrophil cytoplasmic antibodiesN/A

Specimen: serum

No special patient preparation required. Fasting is not necessary for this test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

How long does it take to get results?
Results are typically available within a few days to a week, depending on the laboratory. Your healthcare provider will contact you with the results or discuss them at your follow-up appointment.
Does a positive ANCA mean I have cancer?
No, a positive ANCA test is not a cancer test. It is used to diagnose autoimmune conditions, primarily vasculitis. However, in rare cases, certain infections, inflammatory conditions, or medications can cause a false-positive result. Your doctor will interpret your results in the context of your overall health.
Do I need to fast before this test?
No fasting is required for the ANCA test. You can eat and drink normally before having your blood drawn.
Can this test diagnose vasculitis by itself?
No single test can diagnose vasculitis. The ANCA test is one tool doctors use along with your symptoms, physical examination, imaging studies, and sometimes tissue biopsies to make a diagnosis. A positive ANCA supports the diagnosis but must be confirmed by other findings.
Will I need this test repeated?
Your doctor may order repeat testing to monitor disease activity or treatment response if you have been diagnosed with a condition like vasculitis. The level of ANCA in your blood may change with treatment, so follow-up testing can help your doctor understand how well your treatment is working.
  1. 1
    Mayo Clinic - ANCA testSource
  2. 2
    National Institutes of Health - VasculitisSource
  3. 3
    American College of Rheumatology - ANCA-Associated VasculitisSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy