Key Takeaways

An isolated elevation in the activated partial thromboplastin time (aPTT) in the setting of thrombosis raises concern for antiphospholipid antibody syndrome. Other conditions associated with elevated aPTT and clot – usually distinguishable from the clinical context – include heparin-induced thrombocytopenia, liver disease and disseminated intravascular coagulation.

The antiphospholipid syndrome (APS) is an acquired systemic autoimmune multisystem disorder characterized by arterial, venous, or small vessel thromboembolic events and/or pregnancy morbidity in the presence of persistent antiphospholipid antibodies (aPLs).

Lupus anticoagulant is one of three aPLs recognized in the international diagnostic criteria. The other two are anticardiolipin (aCL) antibodies and anti-beta-2-glycoprotein 1 antibodies.

The LA test correlates better with clinical events compared to aCL and anti-beta-2-GP1 tests.

Lupus anticoagulants cause prolongation of phospholipid-dependent clotting assays in vitro, but are associated with a hypercoagulable state in vivo.

All three criteria aPLs should be tested at the same time.

Patients with APS and venous or arterial thrombosis are typically treated with anticoagulants +/- antiplatelet agents. Warfarin is the preferred agent for long term anticoagulation. DOACs are not currently recommended.

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