This test detects antibodies directed against myeloperoxidase (MPO), an enzyme found in the granules of white blood cells called neutrophils. The presence of these antibodies is strongly associated with Microscopic Polyangiitis (MPA) and Eosinophilic Granulomatosis with Polyangiitis (EGPA, formerly Churg–Strauss syndrome) — autoimmune diseases that cause inflammation and damage of small blood vessels.
Diagnostic Value: Anti-MPO antibodies serve as a key marker for diagnosing certain types of ANCA-associated vasculitis (AAV). Their detection helps distinguish MPA and EGPA from other autoimmune or inflammatory disorders.
Disease Monitoring: Levels of Anti-MPO can rise or fall with disease activity, allowing clinicians to monitor treatment response and detect early signs of relapse.
Symptom Correlation: Patients with Anti-MPO antibodies may experience systemic symptoms such as fatigue, weight loss, fever, neuropathy, cough, and kidney inflammation (glomerulonephritis).
Because of these associations, the Anti-MPO test provides valuable insight into autoimmune vasculitis, helping guide early diagnosis and effective long-term management.