Innovative tests of plasmatic hemostasis

Abstract

Up to this time, plasmatic hemostasis tests often did not reflect physiologic hemostasis: the final thrombin (IIa) activity is far above the physiological thrombin activity generated in recalcified clotting plasma, which is about 0.1 to 0.2 IU/mL thrombin. Using final supramolar concentrations of arginine and chromogenic substrate concentrations below 0.6 mM, an ultra-specific and -sensitive determination of thrombin activity in plasma becomes feasible. In this review, 4 recent plasmatic thrombin assays derived from this principle are presented: basal IIa activity (IIa test), recalcified coagulation activity assay (RECA), intrinsic coagulation activity assay (INCA), and extrinsic coagulation activity assay (EXCA). The EXCA is an especially suitable method for determining the anticoagulant power of any plasmatic anticoagulant that acts against thrombin and/or factor Xa. In addition to these thrombin tests, 2 fibrinogen tests (for function [FIFTA] and antigen [FIATA]) and a global assay for plasmatic fibrinolysis (FIPA-10) have been developed. None of these recent photometric hemostasis assays needs special coagulation analyzers. They add valuable information about the hemostasis state of the individual patient.