Heparin Cofactor During Early Stage of Coagulation in Vitro and During Bleeding in Vivo

Abstract

Heparin cofactor activity is measured with the amidolytic method according to 0degard (1975) during in vitro coagulation and during bleeding.Heparin cofactor activity decreases differently during coagulation process of PRP or PFP. It is suggested this is due to heparin neutralization by PF4 and/or to thrombin formation. Antithrombin III level is not modified.During bleeding, the same phenomenon is observed when the amount of heparin in the buffer is low enough. Decrease in heparin cofactor activity is already observed on a sample collected less than 90 seconds after the puncture, before any detectable thrombin formation.Decrease in heparin cofactor activity during bleeding is studied in pathological conditions. It is more marked in some hypercoagulable states.