Test Findings
 

Positive ANCAs

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Overview

  • Anti-neutrophil cytoplasmic antibodies (ANCAs) are antibodies directed toward cytoplasmic granules of neutrophils and monocytes.
    • Assays

    • Immunofluorescence (indirect) - measures distinctive cytoplasmic (c-ANCA) or perinuclear (p-ANCA) patterns that are not specific to a single antigen
    • ELISA (direct) - measures PR3-ANCA and MPO-ANCA
  • ANCAs are positive in the presence of ANCA-associated small-vessel vasculitis, though may also be positive in other disease. As such, a high clinical suspicion should be present before ordering the test.
    • Interpretation

    • c-ANCA (cytoplasmic) - directed against proteinase 3 (PR3) and several other moleculesStrongly associated with granulomatosis with polyangiitis (previously Wegener's granulomatosis)
    • p-ANCA (peripheral) - directed against myeloperoxidase (MPO) and several other moleculesLess specific, but most strongly associated with microscopic polyangiitis
    • Causes of Positive ANCAs

    • ANCA-Associated Vasculitis

    • Granulomatosis with polyangiitis (previously Wegener's granulomatosis)
    • Microscopic polyangitis (MPA)
    • Eosinophilic granulomatosis with polyangiitis (previously Churg-Strauss syndrome)
    • Drug-induced vasculitis
    • Other

    • Infective endocarditis
    • Tuberculosis
    • Primary sclerosing cholangitis (PSC)
    • Pulmonary fibrosis
    • Ulcerative colitis
    • Rheumatoid arthritis
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