Serum Immunoassay for Anti-Neutrophil Cytoplasmic Antibodies (ANCA) – Specific to Proteinase 3 (PR3)
This test measures antibodies in your blood that target a specific protein found in white blood cells, called Proteinase 3. These antibodies are linked to certain autoimmune conditions affecting blood vessels.
["This test helps diagnose or monitor autoimmune diseases like granulomatosis with polyangiitis (GPA)."]
Key facts at a glance
- LOINC
- 47347-0
- Short code
- S pneum Da 15B IgG 2:1 Ser-Rto
- Synonyms
- S pneum Da 15B IgG 2:1 Ser-Rto
- Category
- coagulation
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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
Why This Test Is Done
Your doctor may order this test if you have symptoms such as persistent sinus or lung infections, unexplained skin rashes, kidney problems, or unexplained blood vessel inflammation. It’s often used alongside other tests to confirm a diagnosis of vasculitis or other autoimmune disorders.
What to Expect Before the Test
No special preparation is needed. You’ll provide a blood sample, typically drawn from a vein in your arm. If you’re on blood thinners, let your doctor know before the test.
What the Test Results Mean
Positive results suggest the presence of PR3-ANCA antibodies, which may indicate conditions like vasculitis. However, false positives can occur, so results are usually interpreted alongside clinical findings and other tests.
Common Conditions Linked to Positive Results
Positive PR3-ANCA is strongly associated with granulomatosis with polyangiitis (GPA), a type of vasculitis that affects small and medium-sized blood vessels. It may also appear in other autoimmune conditions, but further evaluation is needed.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical significance: PR3-ANCA is a key diagnostic marker for vasculitis, particularly GPA. Elevated levels can prompt early treatment to prevent organ damage. However, false positives can occur, so results are validated with clinical correlation and other diagnostic tests.
Short name
PR3-ANCA (Serum)
Frequently asked questions
What does a positive PR3-ANCA result mean for my health?
Will I need to take any special steps if my test is positive?
Can false positives happen with 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