MPO (p-ANCA)

MPO antibodies are formed when the immune system mistakenly attacks the myeloperoxidase enzyme, found inside neutrophils. These antibodies are also called p-ANCA (perinuclear anti-neutrophil cytoplasmic antibodies) due to their perinuclear staining pattern observed during immunofluorescence testing.

The MPO (p-ANCA) test measures antibodies against the myeloperoxidase (MPO) enzyme, which is found in neutrophils (a type of white blood cell) that help fight infections. This test helps diagnose autoimmune diseases, such as GPA and other forms of vasculitis, monitor disease activity, guide treatment decisions, and rule out other conditions that cause similar symptoms, such as infections or other autoimmune diseases.

A doctor may advise a MPO (p-ANCA) test when symptoms of autoimmune vasculitis are present. General symptoms may include fever, fatigue, headache, weight loss, aches, etc. Other symptoms depend on the affected body parts.

No special preparation is required for the MPO (p-ANCA) test. Patients should inform their doctor about all medications (e.g., immunosuppressants, steroids, etc.) and supplements (e.g., biotin, etc.) currently being taken, as some may affect test results, potentially requiring dosage adjustments or temporary discontinuation before the test.

Test result ranges are approximate and may differ slightly between labs, depending on the methodology and laboratory guidelines. Self-medication should be avoided, and a doctor should always be consulted to interpret results correctly.