Correct laboratory approach to APS diagnosis and monitoring.

Triple positivity (positive Lupus Anticoagulant, anticardiolipin and anti β2-glycoptrotein I antibodies) identifies the pathogenic autoantibody (anti Domain I of β2-glycoptroteinI) that is present in patients with definite Antiphospholipid Syndrome (APS). This is supported by the fact that aβ2GPI antibodies obtained by affinity purification in these patients possess LA activity. Moreover, patients and carriers of this profile carry a much higher risk of thrombosis and pregnancy loss than APS patients with positivity for only one of the tests. Thus, very different risk categories exist among patients with APS as well as among carriers of aPL. Clinical studies and interventional trials should first take these high risk subjects into consideration.