The antiphospholipid syndrome: when does the presence of antiphospholipid antibodies require therapy?

To avoid wasting healthcare resources through overinvestigation in otherwise healthy people, it is important to remember that antiphospholipid antibodies (ie, lupus anticoagulant and anticardiolipin antibody) often do not signify clinical disease. However, when features of the antiphospholipid syndrome (APS) are also present, serious thrombosis may be expected. Exactly how these antibodies alter hemostasis to induce a hypercoagulable state remains unclear. Activated partial thromboplastin time may not be a reliable screening test in a minority of patients with lupus anticoagulant and is not useful in screening for anticardiolipin antibodies. When APS is strongly suspected on clinical grounds, definitive tests (ie, enzyme-linked immunosorbent assay for IgG, IgA, and IgM anticardiolipin antibodies and the dilute Russell's viper venom time test) followed by confirmatory tests (eg, for lupus anticoagulant) should be ordered. Patients with APS are at high risk for recurrent thrombosis, but questions about optimal clinical management remain unresolved. High-intensity or lifelong anticoagulation therapy should be considered in some cases. Low-molecular-weight heparin may ultimately prove to be the treatment of choice in pregnant APS patients.