A new global assay of coagulation and fibrinolysis.

INTRODUCTION

Global clotting assays may reflect an individual's net hemostatic balance and could contribute to prothrombotic and hemorrhagic risk assessment. In this research, a global assay that measures both coagulation and fibrinolytic capacities was developed and investigated.

MATERIALS AND METHODS

In the Clot Formation and Lysis (CloFAL) assay, a buffered reactant solution containing trace amounts of calcium, tissue factor, and tissue-type plasminogen activator is added to plasma samples on a 96-well microplate in an automated, thermoregulated (37 degrees C) spectrophotometer. Clot formation and lysis are monitored as continuous changes in absorbance over the course of 3 h. Measurements include maximum amplitude (MA), times to maximum absorbance (T1) and completion of the first phase of decline in absorbance (T2), and area under the curve (AUC), from which a coagulation index (CI) and various fibrinolytic indices (FI) may be calculated.

RESULTS AND CONCLUSIONS

MA, T1, and CI were principally influenced by fibrinogen and procoagulant factors. FI was found to be altered by inhibiting activation of plasminogen or thrombin activatable fibrinolytic inhibitor. Median CI was significantly decreased, while FI was markedly increased, in term neonates as compared to healthy adults (CI: 58% vs. 115%, FI: 210% vs. 90%; P<0.001 for each). By contrast, median CI was notably increased, and FI decreased, in healthy pregnant women when compared to adults (CI: 239% vs. 115%, FI: 59% vs. 90%; P<0.001 for each). The CloFAL global assay is analytically sensitive to several key components in the coagulation and fibrinolytic systems, as well as to physiologic alterations in hemostasis.