Discordance between aPTT and anti-factor Xa levels and implications in patients receiving intravenous unfractionated heparin therapy

Abstract

Heparin, one of the world’s oldest anticoagulation medications, accelerates the rate of inhibition of previously activated clotting factors. It is most often used in the prophylaxis and treatment of thromboembolic disorders and complications associated with atrial fibrillation. The two most common ways to monitor plasma heparin levels and anticoagulation therapy are the activated partial thromboplastin time (aPTT) and anti-factor Xa assay (anti-Xa). This article assesses the performance of aPTT and anti-Xa monitoring protocols and analyzes the discordance between aPTT and anti-Xa levels and its clinical implications in patients receiving intravenous heparin therapy.

Keywords: unfractionated heparin, heparin, aPTT, anti-factor Xa, discordance, clotting