ANCA testing policy

This policy is also available to download in pdf format - ANCA testing policy (pdf; 14 KB)

Within Immunology, requests for Anti-Neutrophil Cytoplasmic Antibodies (ANCA) have become increasingly unfocused and are being used as a screen for vasculitis in a variety of clinical situations with a very low pre-test probability of small vessel vasculitis of the - Microscopic polyangiitis with granulomatosis (Wegener's) spectrum of vasculitides.

Evidence from the literature^1,2,3,4 and our own experience in Oxford strongly suggests that ANCA requests should be confined to patients with a high pre-test probability of small vessel vasculitis, if mis-leading 'false positives' in a range of non vasculitic disorders are to be avoided.

Please note that all ANCA requests are screened within the Laboratory to ensure that testing is restricted to those patients whose presenting features suggest a high pre-test probability of small vessel vasculitis. ANCA requesting should therefore be confined to patients presenting with:

• Chronic necrotising large airways disease
• Cavitating pulmonary nodules
• Subglottic stenosis
• Pulmonary-renal syndrome
• Rapidly progressive glomerulonephritis
• Cutaneous vasculitis accompanied by systemic symptoms
• Mononeuritis multiplex

In order to ensure optimal test usage we will be accepting ANCA requests from the following specialities where the vast majority of patients of the above spectrum will be seen:

• Rheumatology
• Nephrology
• Chest Medicine
• ENT Surgery
• Medical Opthalmology

If you are concerned that your patient requires ANCA testing outside these specialties please supply relevant clinical details to ensure we do not screen out your request, and if still not accepted and you have a strong clinical suspicion for ANCA testing then please do not hesitate to contact the laboratory, or any of the Immunology Medical team, on 01865 225955 to discuss this further.

References

1. Stone JH et al, Test Characteristics of Immunofluorescence and ELISA tests in 856 consecutive patients with possible ANCA associated conditions. Arthritis Care Research 2002; 13: 424-434
2. McLaren JS et al, The Diagnostic value of anti-neutrophil Cytoplasmic antibody testing in a routine clinical setting. QJM 2001: 94: 615-621
3. Sinclair D et al, The effect of a symptom related 'gating policy' on ANCA requests in routine clinical practice. J Clin Path 2004; 57: 131-134
4. 4 Arnold DF et al. Does a gating policy for ANCA overlook patients with ANCA associated vasculitis? An audit of 263 patients. J Clin Pathol. 2010; 63(8): 678-80.