: Cytoplasmic Antineutrophil Cytoplasmic Antibody Screen, Serum
: This test looks for a specific type of antibody (c-ANCA) in your blood. It is used as a screening tool, mainly to help detect certain autoimmune conditions that can cause inflammation of the blood vessels.
[": A positive c-ANCA screen may suggest an autoimmune vasculitis, but results must be interpreted with clinical findings and often require confirmation."]
Key facts at a glance
- LOINC
- 45001-5
- Short code
- C trach IgM Ser IA-aCnc
- Synonyms
- C trach IgM Ser IA-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ia
- CPT
- 82784
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
: What Is Being Tested
: Antineutrophil cytoplasmic antibodies (ANCAs) are antibodies that target certain proteins inside your white blood cells. The "cytoplasmic" pattern (c-ANCA) is a specific pattern seen under the microscope. This test screens your serum (the clear liquid part of blood) for these antibodies using an immunoassay method.
: Why Your Doctor Ordered It
: Your doctor may order this test if you have symptoms that suggest an autoimmune blood vessel inflammation (vasculitis), such as unexplained fever, weight loss, sinus or lung problems, kidney issues, or skin rashes. It is often ordered along with other antibody tests to build a complete picture.
: How to Prepare
: No special preparation is usually required for this blood test. Tell your healthcare provider about any medications you take, since some treatments may affect the results. The test involves a routine blood draw from a vein in your arm.
: Understanding Your Results
: A "negative" screen generally means the antibody was not detected, which makes certain vasculitides less likely but does not rule them out completely. A "positive" screen means antibodies were detected and suggests further evaluation is needed. Because this is a screening test, results are often followed by confirmation methods that your care team will interpret.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
: c-ANCA screening is most commonly associated with a condition called granulomatosis with polyangiitis (formerly Wegener's granulomatosis), and less often with other vasculitides. Because no single test can diagnose these conditions, results are interpreted alongside symptoms, physical exam, imaging, and other laboratory studies. A positive screen alone does not confirm disease, and a negative screen does not exclude it.
Short name
: c-ANCA Screen
Frequently asked questions
: What does a positive c-ANCA screen mean?
: Can medications or infections affect this test?
: Do I need to fast before this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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 16, 2026. · Read our editorial policy