Anti-Proteinase 3 Antibody (Serum) – Immunoassay
This test measures the presence of antibodies against proteinase 3, a protein found in certain white blood cells. These antibodies are linked to a type of autoimmune condition called vasculitis.
["This test helps diagnose or monitor conditions where your immune system mistakenly attacks blood vessels."]
Key facts at a glance
- LOINC
- 46267-1
- Short code
- Proteinase3 Ab Ser IA-aCnc
- Synonyms
- Proteinase3 Ab 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
- 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 Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms like unexplained skin rashes, joint pain, fever, or signs of inflammation in your blood vessels. It’s also used to check if you have a condition called **granulomatosis with polyangiitis (GPA)**, also known as **Wegener’s granulomatosis**, or another form of vasculitis.
What to Expect Before the Test
No special preparation is needed. You’ll have a small needle inserted into a vein (usually in your arm) to draw a blood sample. The process is quick and usually painless. If you’re nervous, let your provider know—they can help make it more comfortable.
What the Test Results Mean
Positive results (meaning antibodies are present) can confirm a diagnosis of vasculitis or help guide treatment decisions. However, false positives can occur, so results are often checked alongside other tests and symptoms. Your provider will discuss the results with you in detail.
Common Conditions Linked to This Test
This test is most commonly used for **granulomatosis with polyangiitis (GPA)**, a type of vasculitis that affects blood vessels in your nose, lungs, and kidneys. It may also be used for other forms of vasculitis or conditions like **microscopic polyangiitis** or **churg-strauss syndrome**.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated antibody levels strongly suggest an autoimmune response targeting proteinase 3, which can damage blood vessels. Early detection is key because treatment can help prevent serious complications like organ damage or life-threatening events. Your provider will use these results alongside other tests to tailor your care plan.
Short name
Anti-PR3 Antibody (Serum)
Frequently asked questions
What does a positive result mean?
Can lifestyle changes affect this test?
How often will I need 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