Main Disease Association
ANCA-associated vasculitis

Category
Antibody

When to Order
* Clinical signs and symptoms of vasculitis, especially small vessel involvement (upper airway vasculitis with epistaxis, pseudotumor, and/or glomerulonephritis, diffuse alveolar hemorrhage, leucocytoclastic vasculitis)

What It Means If Positive
* Recommend ordering more specific testing, such as PR3 antibodies
* MPO antibody is associated with P-ANCA

What It Means If Negative
* Does NOT rule out vasculitides