Abstract
Thrombin activity generated after plasma recalcification is of analytical and clinical interest. Fifty microliters of citrated plasma was recalcified with 5 µL of 250 mM CaCl 2. After 0 to 90 minutes (37°C) 50 µl 2.5 M arginine, pH 8.6, was added. After 20 minutes, thrombin was chromogenically quantified. In normal recalcified plasma, the generated thrombin activity is about 0.1-0.2 IU/ml (37°C) when fibrin generation starts. Pooling of normal plasmas increases the generated thrombin activity about 3-fold. Plasmas of patients on heparin or coumarin generate about 10-fold less thrombin activity. Freezing of pooled plasma at −20°C and thawing at room temperature or 37°C increases thrombin generation approximately 1.5- or 2-fold, respectively. Only thrombin activities in the ascending part of the thrombin generation curve (RECA-t2/RECAt 1>1) are valid. So a prothrombotic state in blood or plasma can be diagnosed.