Serum Anti-PR3 (c-ANCA)

Specimen Required

3-5cc Clotted Blood or Serum

Fasting Required

Purpose of the Test

The serum anti-PR3 test is primarily used to help diagnose and monitor certain autoimmune disorders such as granulomatosis with polyangiitis (GPA), which is a type of vasculitis that affects small and medium-sized blood vessels in various organs, especially the lungs, kidneys, and upper respiratory tract.

When this test is required

The serum anti-PR3 test may be requested when someone has signs and symptoms that suggest GPA or when the healthcare provider wants to monitor disease activity and treatment response in someone who has already been diagnosed with GPA.

What the Test Detects

The serum anti-PR3 test measures the levels of ANCA in the blood that are specific to PR3.

Preparation for the Test

No special preparation is needed for the serum anti-PR3 test. However, the healthcare provider may advise the person to stop taking certain medications that could interfere with the test results.

Sample Requirements

The test requires a blood sample, which is usually drawn from a vein in the arm.

Additional Notes

The serum anti-PR3 test is just one of several tests used to diagnose and monitor GPA. Other tests, such as a complete blood count, renal function tests, urinalysis, imaging studies, and biopsy, may also be needed. The test results should be interpreted in the context of the person’s clinical history, physical examination, and other laboratory tests.

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