SENSITIVITY OF THE FIBRINOGEN CLOTTING TIME - AN IN-VITRO TEST OF POTENTIAL THROMBOGENICITY

The fibrinogen clotting time (FCT) is a measure of thrombin activity, and is used to evaluate the potential thrombogenicity of prothrombin c omplex concentrates (PCC). We have defined end points for clot formati on in this test which allow the measurement in PCC of thrombin concent rations as low as 0.001 IU/ml. The FCT of thrombin and PCC samples whi ch did not contain antithrombin III (ATIII) were the same when measure d at 20 degrees C or 37 degrees C. In the presence of ATIII (0.05 or 0 .25 IU/ml), samples of PCC which were known to contain thrombin showed shorter FCT at 20 degrees C than at 37 degrees C. Inclusion of both A TIII (0.25 IU/ml) and heparin (4 IU/ml) in PCC ensured the complete in activation of endogenous thrombin.