Monitoring plasma heparin concentration in a patient with antiphospholipid syndrome

Excerpt

Antiphospholipid syndrome (APS) is an acquired thrombophilia characterized by the occurrence of arterial and venous events as well as recurrent miscarriages [1, 2]. In the revised classification criteria for APS, lupus anticoagulant (LAC), anti-cardiolipin antibody (aCL), and anti-β2 glycoprotein-I antibody (aβ2GPI) have been utilized as laboratory criteria [1]. Concerning the LAC assay, prolongation of a phospholipid-dependent clotting time such as activated partial thromboplastin time (aPTT) has been commonly used as a screening test [3]. Once patients are diagnosed as having APS, they are recommended to receive prolonged antithrombotic therapy, especially with warfarin [4, 5]. We encountered a patient with APS who could not receive oral warfarin because of malabsorption, and it was also difficult to perform conventional therapeutic monitoring of the heparin dosage using aPTT because of the baseline prolongation of aPTT due to LAC. …