![]() Recognition of the thrombotic disorder currently defined as the antiphospholipid syndrome began with several convergent observations originating from laboratory tests applied from the clinical laboratory. Laboratory Testing for Antiphospholipid Antibodies Anti-β 2-glycoprotein I antibody of IgG and/or IgM isotype in serum or plasma, in a titer >99 th percentile. Lupus anticoagulant present in plasma, on two or more occasions at least 12 weeks apart and detected according to the guidelines of the ISTH Scientific Subcommittee on Lupus Anticoagulants/Phospholipid-Dependent Antibodies ( Table 2).ģ. ![]() Anticardiolipin antibody of IgG and/or IgM isotype in blood, present in medium or high titer, defined as >40 GPL or MPL, or >99 th percentile.Ģ. ![]() Three or more unexplained consecutive spontaneous abortions before the 10 th week of gestation, with maternal anatomic or hormonal abnormalities, and maternal or paternal chromosomal abnormalities excluded.ġ. One or more premature births of a morphologically normal neonate at or before the 10 th week of gestation because of eclampsia or severe pre-eclampsia, or placental insufficiency.Ĭ. One or more unexplained deaths of a morphologically normal fetus at or beyond the 10 th week of gestation, with normal fetal morphology.ī. Vascular thrombosis, defined as one or more clinical episodes of arterial, venous, or small vessel thrombosis, involving any organ and confirmed by appropriate imaging and/or histopathologic analyses.Ī. New tests and diagnostic strategies are in various stages of development and should help improve our ability to accurately diagnose this important clinical disorder.ġ. In addition to understanding limitations of the assays, clinicians also need to be aware of which patients should be tested and not obtain testing on patients unlikely to have APS. For example, lupus anticoagulant testing can be difficult to interpret in patients receiving anticoagulant therapy, but most patients with a thromboembolic event will already be anticoagulated before the decision to perform the tests has been made. Although these assays have been used clinically for many years, there are still problems with the accurate diagnosis of patients with this syndrome. These assays have their origins beginning more than sixty years ago, with the identification of the biologic false positive test for syphilis, the observation of ‘circulating anticoagulants’ in certain patients with systemic lupus erythematosus, the identification of cardiolipin as a key component in the serologic test for syphilis, and the recognition and characterization of a ‘cofactor’ for antibody binding to phospholipids. Diagnostic tests for the detection of antiphospholipid antibodies include laboratory assays that detect anticardiolipin antibodies, lupus anticoagulants, and anti-β 2-glycoprotein I antibodies. The Antiphospholipid Syndrome (APS) is diagnosed in patients with recurrent thromboembolic events and/or pregnancy loss in the presence of persistent laboratory evidence for antiphospholipid antibodies.
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