Mobile Site ›
Print Friendly View

Test ID: VASC    
Antineutrophil Cytoplasmic Antibodies Vasculitis Panel, Serum

‹ Back to Pediatric index

Useful For Suggests clinical disorders or settings where the test may be helpful

Evaluating patients suspected of having autoimmune vasculitis, both Wegener’s granulomatosis and microscopic polyangiitis

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Antineutrophil cytoplasmic antibodies (ANCA) occur in patients with autoimmune vasculitis including Wegener's granulomatosis (WG), microscopic polyangiitis (MPA), or organ-limited variants thereof such as pauci-immune necrotizing glomerulonephritis.(1) ANCA react with enzymes in the cytoplasmic granules of human neutrophils including proteinase 3 (PR3), myeloperoxidase (MPO), elastase, and cathepsin G.

 

Autoantibodies to PR3 occur in patients with WG (both classical WG and WG with limited end-organ involvement) and produce a characteristic pattern of granular cytoplasmic fluorescence on ethanol-fixed neutrophils called the cANCA pattern. Antibodies to MPO occur predominately in patients with MPA and produce a pattern of perinuclear cytoplasmic fluorescence on ethanol-fixed neutrophils called the pANCA pattern.

 

Autoantibodies to PR3 and MPO can also be detected by EIA methods and are referred to as PR3 ANCA and MPO ANCA, respectively.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

MYELOPEROXIDASE ANTIBODIES, IgG

<0.4 U (negative)

0.4-0.9 U (equivocal)

> or =1.0 U (positive) 

Reference values apply to all ages.

 

PROTEINASE 3 ANTIBODIES, IgG

<0.4 U (negative)

0.4-0.9 U (equivocal)

> or =1.0 U (positive) 

Reference values apply to all ages.

Interpretation Provides information to assist in interpretation of the test results

Positive results for proteinase 3 (PR3) antineutrophil cytoplasmic antibodies (ANCA) and cANCA or pANCA are consistent with the diagnosis of Wegener's granulomatosis (WG), either systemic WG with respiratory and renal involvement or limited WG with more restricted end-organ involvement.

 

Positive results for MPO ANCA and pANCA are consistent with the diagnosis of autoimmune vasculitis including microscopic polyangiitis (MPA) or pauci-immune necrotizing glomerulonephritis.

 

A positive result for PR3 ANCA or MPO ANCA has been shown to detect 89% of patients with active WG or MPA (with or without renal involvement) with fewer than 1% false-positive results in patients with other diseases.(1)

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Sequential measurements of titers of antineutrophil cytoplasmic antibodies (cANCA) are useful to monitor the response to treatment in patients with Wegener's granulomatosis (WG). While titers often decrease following successful treatment, the results cannot be relied upon in all cases to determine the response to therapy. In individual patients, the titers of cANCA may not correlate well with response to treatment. The results of proteinase 3 (PR3) ANCA (an autoantibody with a cANCA pattern) by EIA have not been shown to be useful for monitoring disease activity. Accordingly, for monitoring disease activity we advise physicians to order ANCA / Cytoplasmic Neutrophil Antibodies, Serum or MPO / Myeloperoxidase Antibodies, IgG, Serum (the ANCA vasculitis test panel is not appropriate for monitoring disease activity).

 

The ANCA vasculitis test panel cannot be relied upon exclusively to establish the diagnosis of autoimmune vasculitis (WG or microscopic polyangiitis: MPA). Some patients with WG or MPA may not have a measurable titer of antibodies detected by this panel of tests. Some of these patients have antibodies to other neutrophil antigens not included in the panel, eg, neutrophil elastase.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Russell KA, Wiegert E, Schroeder DR, et al: Detection of anti-neutrophil cytoplasmic antibodies under actual clinical testing conditions. Clin Immunol 2002 May;103(2):196-203

2. Specks U, Homburger HA, DeRemee RA: Implications of cANCA testing for the classifications of Wegner's Granulomatosis: performance of different detection systems. Adv Exp Med Biol 1993;336:65-70