Do not request the dosage of ANCA (antibodies against the cytoplasm of neutrophils) only in the presence of a clinical suspicion of connectivitis, without adequate and documented evaluation or evident clinical suspect of a vasculitis.

Type of practice

Laboratory tests



Topic Area


As is well known, ANCAs are associated with a group of small vessel vasculites called ANCA-associated vasculitis, which include microscopic polyangiitis, granulomatosis with polyangiitis (M. of Wegener) and eosinophilic granulomatosis with polyangiitis (m. Churg-Strauss). Several studies have shown that the diagnostic usefulness of ANCA increases with the increase in the clinical suspicion of such diseases, being maximal, for example, in patients with multiple symptoms of m. of Wegener, where a 98% post-test probability was demonstrated, but very low in patients with only one symptom of m. of Wegener, with a post-test probability of only 7-16%. Associated ANCA vasculitates are very rare diseases and the research of ANCAs in the general population gives rise to a high percentage of false positives. Therefore adequate prescriptive behavior can only move from evidence of at least two clinical signs characterizing a vasculitis.


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Attention. Please note that these items are provided only for information and are not intended as a substitute for consultation with a clinician. Patients with any specific questions about the items on this list or their individual situation should consult their clinician.