A comparison of the sulphite and thrombin methods for measuring fibrinogen concentration of plasma from patients undergoing thrombolytic therapy.

A thrombin method for the determination of fibrinogen concentration has been compared with a non-enzymatic sulphite precipitation method on plasma from patients undergoing thrombolytic therapy with an intermittent plasminogen/streptokinase regime. There was very good agreement between the methods even when the determinations were made in the presence of high levels of fibrinogen degradation products (FDP), provided that the thrombin clottable fibrinogen was greater than 1 mg/ml. However, after extensive fibrinogen depletion, when the thrombin method underestimates fibrinogen concentration due to significant clot inhibition by FDP, an overestimate due to co-precipitation of fragments X and Y will be obtained by the sulphite method. This suggests that the simultaneous application of both techniques may provide a simple method of assessing the presence of high levels of anticoagulant FDP in various clinical disorders.