Clinical Utility of Laboratory Tests Used to Identify Antiphospholipid Antibodies and to Diagnose the Antiphospholipid Syndrome

Abstract

The antiphospholipid syndrome (APS) is defined by thrombotic and/or obstetric events together with the presence of antiphospholipid antibodies in plasma of patients. The original laboratory criteria of APS included lupus anticoagulants (LA) and/or IgG/IgM anticardiolipin antibodies (aCL). They were recently updated with the addition of IgG/IgM anti-beta2 glycoprotein I antibodies (anti-beta2GPI), a better definition of "medium to high antibody titer," and the extension to 12 weeks of the "persistence in time." The revised criteria represent an improvement; however, the potential overdiagnosis of APS remains possible, thus putting patients at risk of overtreatment. To reduce this possibility, proposals have been made to implement strict guidelines for the performance of the LA assay, to exclude aCL measurements in their current application from the criteria, and to limit the measurement of anti-beta2GPI to the G isotype. This should also help in simplifying the laboratory workup of patients being investigated for APS.