A study of two methods for estimating plasma fibrinogen and the effect of epsilon aminocaproic acid and protamine.

Fibrinogen concentrations were determined in normal plasma and in plasma from patients with high and low levels. There was a good correlation between the results of a rapid semi-quantitative fibrinogen titre technique and those of a quantitative assay of coagulable fibrinogen. In normal subjects fibrinogen levels were not significantly influenced by taking blood into epsilon aminocaproic acid (EACA) or by the addition of protamine to plasma. In patients with the defibrination syndrome in whom increased plasma fibrinolysis was not detected, fibrinogen levels were not affected by taking blood into EACA but considerably increased levels were observed after the addition of protamine to plasma. In patients undergoing thrombolytic therapy the fibrinogen levels measured were increased both in blood taken into EACA and in plasma containing protamine. It is suggested that EACA acted by preventing lysis in vitro whilst protamine counteracted abnormal fibrin polymerization. The pattern of results may be of diagnostic importance.