The Amount of Fibrin Necessary to Give a Positive Ethanol Gelation Test at Various Fibrinogen Levels

The minimum fibrin-fibrinogen ratio (f-F ratio) required to give a positive ethanol gelation test at various fibrinogen concentrations was studied. Due to the fact that quantitation of soluble fibrin in plasma is difficult, highly purified fibrinogen was used. However, since a plasma milieu is required to achieve clear cut results with ethanol gelation (with purified fibrinogen alone, precipitation occurs), heat-defibrinated, dialysed and lyophilized normal plasma was added. With this artificial plasma, which in all relevant respects proved very similar to plasma obtained from healthy donors, ethanol gelation was not observed at the highest attainable fibrinogen concentration (1150 mg/100 ml). At fibrinogen levels down to 5-600 mg%, the minimum f-F ratio remained almost constant, but increased gradually by further lowering the fibrinogen concentration. At fibrinogen levels around 50 mg%, the ethanol gelation test remained negative, even in samples saturated with soluble fibrin, i.e. those containing visible fibrin threads.