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Serum Proteinase 3 (PR3) Antibody Level (Qualitative or Quantitative)

Published: August 9, 2026Updated: August 16, 2026

This test measures the presence or level of antibodies against Proteinase 3, a protein found in white blood cells. It is often used to help diagnose conditions like certain types of vasculitis.

Quick summary

["This test helps identify autoimmune conditions affecting blood vessels."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
63309-9
Short code
Proteinase3 Ab Fld Ql IA
Synonyms
Proteinase3 Ab Fld Ql IA
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 Is This Test Done?

Your healthcare provider may order this test if you have symptoms such as joint pain, rash, or unexplained inflammation. It may also be used to monitor conditions like granulomatosis with polyangiitis (GPA), microscopic polyangiitis, or Churg-Strauss syndrome, which involve inflammation of blood vessels.

What Does the Test Involve?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it is analyzed to detect PR3 antibodies. The test can be qualitative (yes/no) or quantitative (measuring exact levels).

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for a few hours before the blood draw if instructed by your provider, but this is not always required for antibody tests.

What to Expect During the Test

You will lie down comfortably while a healthcare provider inserts a needle into your arm to draw blood. The process is quick and typically causes only minor discomfort. You may feel a slight pinch or sting.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

PR3 Antibody Test

Frequently asked questions

What does a positive result mean?
A positive result indicates the presence of PR3 antibodies in your blood, which may signal an autoimmune condition like vasculitis. Your doctor will discuss this with you and may recommend further testing or treatment options.
How often will I need this test?
The frequency depends on your condition and treatment plan. Some patients may need this test periodically to monitor their response to treatment or disease activity. Your healthcare provider will determine the schedule.
Can lifestyle changes affect this test?
While lifestyle factors like diet or stress may influence overall health, they typically do not directly affect antibody test results. However, following your doctor’s advice for managing symptoms and treatment is important.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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 16, 2026. · Read our editorial policy