Diagnosis of antiphospholipid antibodies.

The antiphospholipid antibody syndrome consists of a presentation with venous thrombosis, arterial thrombosis (or vasculopathy), recurrent pregnancy loss, or thrombocytopenia, in the setting of high-titer anticardiolipin antibody or lupus anticoagulant. Characteristics of the lupus anticoagulant (an antibody detected by a functional assay) and anticardiolipin antibody are reviewed, in light of new information on the role of plasma proteins, especially B2-glycoprotein I. The advantages and disadvantages of screening and confirmatory assays for lupus anticoagulant are detailed, as well as modifications of the anticardiolipin antibody assay to improve sensitivity and specificity.