Antineutrophil cytoplasmic antibodies (ANCA) - serum

Last updated: Monday, 12, June, 2006

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Item Process
Specimen

5 mL blood in plain tube.

Method

Indirect IF for detection of reaction pattern (c-ANCA, p-ANCA and atypical). Immunoassay to determine specificity (antiproteinase 3, antimyeloperoxidase).

Reference Interval

Method dependent.

Application

Assessment of patients with suspected systemic necrotising vasculitis and renal disease; microscopic polyangiitis, idiopathic necrotising and crescentic glomerulonephritis.

Interpretation

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.

Reference

Savage, C O S. Harper, L. Cockwell, P. Adu, D. Howie, A J. Vasculitis . BMJ. 320(7245):1325-1328, May 13, 2000.