From the Research
In patients with positive myeloperoxidase (MPO) antibodies and low-grade fevers, a thorough evaluation for ANCA-associated vasculitis should be conducted, particularly microscopic polyangiitis (MPA) or granulomatosis with polyangiitis (GPA). Initial assessment should include a complete physical examination focusing on pulmonary, renal, and skin manifestations, along with comprehensive laboratory testing including complete blood count, comprehensive metabolic panel, urinalysis, inflammatory markers (ESR, CRP), and renal function tests. Chest imaging and possibly renal biopsy may be necessary to assess organ involvement. If vasculitis is confirmed, treatment typically involves induction therapy with cyclophosphamide (1.5-2 mg/kg/day orally or 15 mg/kg IV every 2-3 weeks) or rituximab (375 mg/m² weekly for 4 weeks), combined with corticosteroids (prednisone 1 mg/kg/day, maximum 60-80 mg daily, with gradual taper). Maintenance therapy follows with azathioprine (2 mg/kg/day), methotrexate (20-25 mg weekly), or mycophenolate mofetil (1-2 g/day). Patients require regular monitoring for disease activity and medication side effects. The presence of MPO antibodies suggests autoimmune activity against neutrophil components, leading to inflammation of small blood vessels, which explains the systemic symptoms including low-grade fevers, as supported by the latest evidence on the role of myeloperoxidase in inflammation and oxidative stress 1, 2.
Some key points to consider in the evaluation and management of these patients include:
- The potential for MPO-ANCA to be associated with interstitial lung disease (ILD) without ANCA-associated vasculitis, as noted in a recent review 1
- The link between myeloperoxidase and cardiovascular disease, including the potential for MPO to contribute to atherogenesis and endothelial dysfunction 2
- The emerging role of myeloperoxidase in cancer pathogenesis, although this is still an area of ongoing research 3
- The prognostic value of myeloperoxidase in patients with peripheral artery disease, with higher levels associated with increased risk of major adverse cardiac events and limb ischemia 4
Overall, a comprehensive approach to diagnosis and treatment, taking into account the latest evidence on the role of myeloperoxidase in various diseases, is essential for optimizing outcomes in patients with positive MPO antibodies and low-grade fevers.