Methods for improving the sensitivity and specificity of the fibrin plate.

Fibrinogen prepared by the method of Blombäck and Blombäck is most suitable with respect to sensitivity and stability for the estimation of urokinase by the fibrin plate technique. Adding plasminogen to a concentration of around 0.5 casein units/ml 0.2 g% clottable fibrinogen provides substrate conditions of optimal sensitivity and reproducibility.