Laboratory testing and identification of antiphospholipid antibodies and the antiphospholipid syndrome: a potpourri of problems, a compilation of possible solutions

The antiphospholipid syndrome (APS) is an autoimmune condition characterized by vascular thromboses and/or pregnancy morbidity, and its diagnosis currently requires laboratory evidence of the presence of antiphospholipid antibodies (aPL). aPL are in turn identified using a large number of laboratory procedures based on one of two distinct test processes, namely solid-phase assays and liquid-phase assays. The former includes anticardiolipin antibodies and anti-beta2 glycoprotein I antibodies, and the latter are centered on clot-based tests that are used to identify the so-called lupus anticoagulant. The current article provides an overview of the laboratory testing and identification of aPL, and in particular the limitations, standardization, and clinical utility of such testing. We also review preanalytical, analytical, and postanalytical issues that compromise the clinical utility of these tests. Finally, we provide a list of recommendations aimed to foster broader international cooperation to assist in the preparation of integrated guidelines, for both solid-phase and liquid-phase assays, and for laboratory testing, clinical ordering, and interpretation.