ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES (ANCA) - serum

---

Specimen: 5 mL blood in plain tube.

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

Reference Interval: Consult pathologist.

Application: Assessment of patients with suspected vasculitis and renal disease; microscopic polyarteritis; idiopathic necrotising and crescentic glomerulonephritis .

Interpretation: Cytoplasmic staining (c-ANCA) is associated with antiproteinase 3 antibody and 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. The different ANCA patterns are not entirely sensitive or specific for any particular form of vasculitis. In a suggestive clinical context, ANCA positivity should be used to select those patients requiring more intensive investigation, including tissue biopsy, to exclude systemic necrotising vasculitis.

Reference: Falk RJ and Jennette JC. Annu Rev Med 1991; 42: 459-469.

---