PR3 (c ANCA)

Clinical definition of the PR3 (c-ANCA) test
Antineutrophil cytoplasmic antibodies (ANCA) are a group of autoantibodies produced when a person’s immune system mistakenly targets and attacks the neutrophil protein, proteinase 3 (PR3). This results in the production of autoantibodies to   PR3.  The PR3 (C-ANCA) blood test detects the presence or absence of these autoantibodies. These autoantibodies are present in a variety of autoimmune disorders that cause inflammation and damage to blood vessels throughout the body (systemic vasculitis). Vasculitis causes tissue and organ damage due to the narrowing and obstruction of blood vessels and the subsequent loss of blood supply.

 Why is the PR3 (c-ANCA) test done?
A PR3 (C-ANCA)test is carried out to evaluate systemic autoimmune Vasculitis and other autoimmune disorders (Autoimmune disorders are diseases caused by the body producing an inappropriate immune response against its own tissues) such as Wegener's Granulomatosis (WG), Microscopic Polyangitis (MPA), and a number of others.

What are the common signs/symptoms when the PR3 (c-ANCA) test is done?

  • Eyes — red, itchy eyes or "pink eye" (conjunctivitis); problems with sight (blurry vision, loss of vision)
  • Ears — hearing loss
  • Nose — runny nose or other persistent upper respiratory symptoms that do not go away
  • Skin — rashes and/or granulomas
  • Lungs — cough and/or difficulty breathing
  • Kidneys — abnormal amounts of protein in the urine
  • Fatigue
  • Fever
  • Weight loss
  • Muscle aches
  • Night sweats

What should I do before the PR3 (c-ANCA) test?

Specimen type

Specimen collection procedure

Preparatory instructions before the test *

Serum (Blood Sample)


Collection of blood from a vein, usually from the arm.

No Fasting Required.

No other special preparations required.

* Subjects suffering from any illness or on oral or injectable medications are advised to consult their physician prior to requesting any tests or procedures.

How do I interpret my PR3 (c-ANCA) test results?

Reference Range*


Below 20 RU/mL **


20 & Above RU/mL


‘*A Reference range is a set of values which helps the healthcare professional to interpret a medical test. It may vary with age, gender, and other factors. Reference ranges may also vary between labs, in value & units depending on instruments used and method of establishment of reference ranges’

Diseases/conditions related to the PR3 (c-ANCA) test

  • Systemic Vasculitis
  • Aneurysms
  • Wegener's Granulomatosis (WG)
  • Churg-Strauss syndrome 
  • Microscopic Polyangitis (MPA)

Other tests related to the PR3 (c-ANCA) test

  • Autoantibodies
  • Urinalysis
  • ESR (erythrocyte sedimentation rate)
  • CBC (complete blood count)
  • BUN (blood urea nitrogen)
  • Creatinine

Synonyms : C- Antineutrophil Cytoplasmic Antibodies, Serine Protease 3