Antiphospholipıd Syndrome and Venous Thrombosis

Abstract

Antiphospholipid syndrome(APLS) is a prothrombotic state characterized by recurrent venous thrombotic events including deep venous thrombosis, as well as pulmonary embolism, arterial thrombosis, recurrent fatal loss due to placental thrombosis and the presence of circulating antiphospholipid antibodies(APA) (Roubey RAS, 2001). As both thrombosis and pregnancy morbidity have a large number of other origins, the diagnosis of APLS relies on the quality and reliability of the laboratory investigations, on the persistent positivity of the APA assays, and sometimes on the lack of any other cause. Although a broad spectrum of APA exists, the universally accepted diagnostic APA tests are lupus anticoagulant(LA) functional coagulation assay; anticardiolipin antibody(ACA) enzymelinked immunosorbent assay(ELISA); and anti-┚2-glycoprotein I antibody(a┚2GPI) ELISA. Antiphospholipid antibodies were first described in 1906 in patients with syphilis. These complement-fixing antibodies reacting with extracts from bovine hearts(mitochondrial phospholipid cardiolipin) formed the basis for the serologic syphilis test(Venereal Disease Research Laboratory-VDRL assay). Mass population screening for syphilis demonstrated that patients with systemic lupus erythematosus(SLE) without clinical syphilis had persistently false-positive VDRL tests(Haserick J,et al 1952, Baker WF, et al 2008). As falsepositive VDRL tests in patients with SLE were also found to be associated with prolonged in vitro coagulation, the term ‘lupus anticoagulant’ was introduced. The lupus anticoagulant is an antibody that prolongs phospholipid dependent coagulation tests in vitro. It was given this name in 1972 because clear proof of its site of action was lacking, and because the anticoagulant had been recognized in patients with systemic lupus erythematosus(Donald I Feinstein 2009 ). It is a misnomer because the lupus anticoagulant is more frequently encountered in patients without lupus and is associated with thrombosis rather than with bleeding. Immunoglobulins reacting with other hemostatic factors, such as von Willebrand factor (VWF), factor VIII, factor IX, and factor XI, inhibitors of thrombin and fibrin polymerization, and factor XIII have also been described in patients with SLE(Donald I Feinstein 2009), but they are rare compared with the lupus anticoagulant. Patients with the lupus anticoagulant who do not have established SLE fall into several different categories: (1) patients with “lupus-like”chronic autoimmune disorders but without findings that fit the criteria for the diagnosis of SLE; (2) patients with other chronic systemic autoimmune disorders; (3) patients presenting with a venous or arterial thrombotic