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Anti-Neutrophil Cytoplasmic Antibody

ANCA, c-ANCA, p-ANCA, Anti-Neutrophil Cytoplasmic Antibody (ANCA)

Test Codes

EPIC: LAB458, SOFT: ANCA, Antrim #31363

Department

Immunology

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 2.0 mL)

Physician Office/Draw Specimen Preparation

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8°C or 36-46°F). (Minimum Serum: 0.5 mL)

Rejection Criteria

• Plasma specimens.
• Severely lipemic, icteric or hemolyzed specimens. 

In-Lab Processing

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Room temperature is acceptable for a maximum of two hours. (Minimum Serum: 0.5 mL)

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers^® with Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers^® without Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 3 months

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Special Chemistry Laboratory

Performed

Monday, Wednesday, Friday.
Results available within 24 hours (if negative).

Reference Range

Less than 1:20.

Test Methodology

Indirect Immunofluorescent Assay (IFA).

Interpretation

The presence of ANCA antibodies in patients with certain necrotizing vasculitides can be an important diagnostic aid for establishing a subtype-specific diagnosis and for monitoring disease activity. ANCAs of 1:40 are not considered clinically significant. Anti-Neutrophil Cytoplasmic Antibodies (c-ANCA= granular cytoplasmic staining, p-ANCA= Perinuclear staining) are found in the serum of over 90% of patients with certain necrotizing systemic vasculitides, and usually in less than 5% of patients with collagen vascular disease or arthritis.

Clinical Utility

• Anti-Neutrophil Cytoplasmic Antibody (ANCA) testing is of value in detecting Wegener's granulomatosis (WG) and other vasculitic diseases.
• Anti-neutrophil cytoplasmic antibodies are autoantibodies specific for neutrophil lysosomal enzymes, particularly for proteinase 3 (PR3, a serine protease) and myeloperoxidase (MPO). Cross-reaction has also been seen with cationic protein 57 (CAP 57), cathepsin G, elastase, lactoferrin, and other lysosomal proteins. ANCA IFA patterns have been subdivided into two patterns on ethanol-fixed neutrophils. The cytoplasmic pattern is designated c-ANCA while the perinuclear pattern is referred to as p-ANCA. The perinuclear pattern reverts to a c-ANCA pattern on formalin-fixed neutrophils. Generally speaking, c-ANCA is specific for the PR3 protein while p-ANCA reacts with MPO.
• The clinical value of ANCA (see additional information above) has been studied most in patients with WG or WG variants as well as those with microscopic polyangiitis. In patients with WG, there is a close association with the presence of c-ANCA. The association is strongest in patients with generalized disease and the sensitivity decreases somewhat with localized or inactive disease states.
• Although the specificity of c-ANCA for WG was originally thought to be very high, c-ANCA can be found in patients without classic WG. For example, a small percentage of patients with idiopathic necrotizing and crescentic glomerulonephritis (NCGN) will have c-ANCA and PR3 antibodies. NCGN is generally considered to be a renal-limited form of microscopic polyangiitis, although some patients will evolve into WG.
• Microscopic polyangiitis is often ANCA-positive with approximately an equal distribution of c-ANCA and p-ANCA. As with cases of NCGN, some microscopic polyangiitis cases with antibody to PR3 will evolve into WG. Churg-Strauss syndrome is associated with MPO antibody.
• Numerous reports indicate that effective treatment of WG is associated with falling ANCA titers. However, the usefulness of monitoring titers in patients in remission is controversial. Some authors have shown that rising titers is indicative of relapse within months. However, not all patients with rising titers will relapse.
• P-ANCA is not specific for any disease; however, P-ANCA with specificity for MPO is associated with microscopic polyarteritis, rapidly progressive glomerulonephritis, Churg-Strauss syndrome and polyarteritis nodosa. In patients with antinuclear antibodies (ANA), it is difficult to discern ANCA antibodies which produce a perinuclear (P-ANCA) pattern; however, the detection of MPO antibodies strongly suggests the presence of P-ANCA in these cases.
• An atypical P-ANCA pattern is detected in approximately 60-85% of ulcerative colitis and primary sclerosing cholangitis; this P-ANCA pattern is also seen in 10-20% of patients with Crohn's disease.

CPT Codes

86255 (Screen), 86256 (Titer).

Contacts

Last Updated

10/16/2024