Abstract
A simple method for the quantification of antithrombin activity was demonstrated by means of fibrinogen agarose plate. The principle of the method is the growth of fibrin rings by residual thrombin on fibrinogen agarose plate after the reaction with antithrombin. The mixtures of defibrinated plasma or serum, and thrombin were incubated for about 30min at 37°C, and then poured into the wells in the fibrinogen agarose plate with micropipettes. After the incubation of the plate for about one hr at 37°C, the diameters of fibrin rings were measured. As a control, saline was used in place of samples. The antithrombin activity index was indicated by the square of the control diameter which was divided by that of the sample diameter. The reproducibility of the method was 4.8% in coefficient of variation in plasma and 5.4% in serum, and normal values were estimated as 1.5-2.5 in plasma and 1.4-2.0 in serum. There was a significant correlation between the values obtained with this method and with the biological one by Biggs et al. With this method we tested about 70 samples from patients. In cases of liver cirrhosis and disseminated intravascular coagulation (DIC), antithrombin activity index decreased.
