If the sample is received in the department by 3pm, an urgent result can usually be made available the following day (or the same day if received earlier). If an urgent ANCA is required the same day, please telephone the laboratory with an expected time of receipt.
In cases where the ANCA screen result is positive or equivocal, samples are automatically tested for MPO and PR3 antibodies.
There are two diagnostically significant ANCAs:
1. Antibodies to neutrophil myeloperoxidase (anti-MPO), which typically give a perinuclear pattern on immunofluorescence (pANCA). They are predominantly associated with microscopic polyangiitis and necrotising crescentic glomerulonephritis (or rapidly progressing glomerulonephritis RPGN), but are also present in about 60 % of cases of Churg-Strauss vasculitis.
2. Antibodies to proteinase 3 (anti-PR3), which typically give a cytoplasmic pattern on immunofluorescence (cANCA). They are predominantly associated with Granulomatosis with Polyangiitis (GPA, formally known as Wegener s granulomatosis), but also found in some patients with microscopic polyangiitis and Eosinophilic Granulomatosis with Polyangiitis (EGPA, formally known as Churg- Strauss vasculitis). Sometimes a cANCA pattern will be reported with negative antibodies (to PR3 and MPO) this is of uncertain significance. However, a pANCA with negative antibodies is not unusual in inflammatory bowel disease (especially ulcerative colitis) or primary sclerosing cholangitis.
A negative ANCA does not exclude a diagnosis of vasculitis some well characterised vasculitides are typically ANCA-negative, e.g. polyarteritis nodosa and rheumatoid vasculitis.
An on-call service is available for clinically urgent ANCA (MPO and PR3 antibodies) and
GBM requests on Saturdays, Sundays and Bank holidays between 9am and 5pm (after
1.30pm, advice only). To access this service, ring switchboard and ask for IMMUNOLOGY
URGENT ANCA ON-CALL (not transplant immunology) and please stay on the line until your
call is connected to the on-call Biomedical Scientist.
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