Comparison of the reaction-rate and clot-density methods for determination of plasma fibrinogen.

The reaction-rate (Dade) and clot-density (Sherwood) methods for determining plasma fibrinogen were compared. Both require small sample volumes, are economical, and may be performed using commercially standardized instruments and reagents. Equivalent times were required for sample preparation. The results of the fibrinogen determinations were similar for plasmas of normal subjects, reference plasmas, those from patients with and without disseminated intravascular coagulation, and solutions of bovine fibrinogen. Both procedures could be made more economical by adjusting the amounts of certain reagents in the kits. High fibrin degradation product levels had no effect on the fibrinogen determination by either method. Advantages of the Sherwood method included digital readout (obviating further calculations) and the fact that the change in clot density could be plotted. The Dade method had the advantages of being less affected by high concentrations of heparin, being applicable to either citrated or oxalated plasma, requiring considerably less time (especially for certain abnormal plasmas), and requiring less technical sophistication.