Antineutrophil cytoplasmic antibodies (ANCA) - serum

5 mL blood in plain tube.

Method dependent.

Cytoplasmic staining (c-ANCA) is frequently associated with antiproteinase 3 antibody and in an appropriate clinical context consistent with renal vasculitis, is a sensitive and specific test for Wegener's granulomatosis. Perinuclear staining (p-ANCA) is associated with a number of antibodies, including antimyeloperoxidase antibody; although it is found in patients with microscopic polyangiitis, it may also be present in a number of other renal, systemic and rheumatic disorders.
Positive immunoassays more closely correlate with the presence of systemic necrotising vasculitis.
In a suggestive clinical context, ANCA positivity should be used to select those patients requiring more intensive investigation, including renal biopsy, to exclude systemic necrotising vasculitis. Atypical ANCA is associated with a variety of diseases other than vasculitis. A negative ANCA result does not exclude the diagnosis of systemic necrotising vasculitis.