Anti-Proteinase 3 Antibody (Serum) - Qualitative

Why This Test Is Done

Your doctor may order this test if you have symptoms of inflammation in your blood vessels, such as rash, joint pain, or unexplained fevers. It can also be used to confirm a suspected diagnosis of conditions like granulomatosis with polyangiitis (formerly known as Wegener’s granulomatosis).

What to Expect Before the Test

No special preparation is needed for this test. You may have a blood sample drawn from a vein in your arm, similar to other routine blood tests. If you’re on blood thinners, let your doctor know before the test to avoid unnecessary precautions.

What the Test Results Mean

A positive result means your body has produced antibodies against Proteinase 3, which may indicate an autoimmune condition affecting blood vessels. A negative result suggests no detectable antibodies, but it doesn’t rule out other possible causes of symptoms.

Possible Conditions Linked to This Test

Positive results are most commonly associated with vasculitis, a group of rare diseases that cause inflammation in blood vessels. This can affect organs like the lungs, kidneys, or skin. Doctors use these results alongside other tests and symptoms to make a diagnosis.