Laboratory diagnosis of antiphospholipid syndrome.

Antiphospholipid syndrome is an intriguing clinical entity encountered by all physicians because of the wide range of clinical manifestations involving every organ system. Ordering a single test under the name "antiphospholipid antibody" does not rule out this entity. There are overlapping but distinct autoantibodies, and a positive result in one assay is conclusive despite a negative result in another. Laboratories continue to conduct several nonstandard tests as part of integrated kits and physicians should be familiar with them for proper interpretation of the results. Lupus anticoagulant testing is an integral part of every thrombophilia workup and should be performed regardless of the screening activated partial thromboplastin time or mixing study.