Antiphospholipid syndrome


  • APS definition (need 1 from each category):
    • Presence of at least 1 of the following: DVT, arterial thrombosis, or pregnancy morbidity (eg fetal loss, preterm)
    • Presence of at least 1 of the following antiphospholipid antibodies (aPL): lupus anticoagulant (LA), anticardiolipin (aCL), β2-glycoprotein-1 (β2-GP-1)
  • APS can occur as a primary condition or in setting of underlying disease (eg SLE)
  • Lifelong anticoagulation with warfarin, with the following target INRs[1]
    • 2.0-3.0 for venous
    • 3.0 for arterial
    • 3.0-4.0 recurrent thrombosis
    • ASA plus warfarin for severe/refractory cases


  • Currently accepted theory: Susceptible patients (eg SLE) develop aPL after infection. After development of aPL, “second hit” stress required to develop full-blown APS. aPL affects coagulation by interacting with protein C, annexin V, platelets, proteases, tissue factor, and impairing fibrinolysis
    • “Second hit” stressors: smoking, prolonged immobilization, pregnancy, exogenous estrogen, malignancy, nephrotic syndrome, hypertension, hyperlipidemia

Clinical Features

Differential Diagnosis

Microangiopathic Hemolytic Anemia (MAHA)


Catastrophic APS Treatment


  • Acute complications, admission with hematology consult


  • Catastrophic APS: widespread thrombotic disease with multiorgan failure precipitated by some stress (eg infection)

See Also

  1. Movva S et a. Antiphospholipid Syndrome. eMedicine. Mar 24, 2015.