Comparison of the kinetic fibrinogen assay with the von Clauss method and the clot recovery method in plasma of patients with conditions affecting fibrinogen coagulability.

Abstract

A Kinetic Fibrinogen Assay (KFA), a method based on the kinetic reaction of the developing fibrin clot, was used to determine fibrinogen concentration in plasma. Two other methods employing different quantification principles were used for comparison: the von Clauss method and the procedure measuring protein concentration in an isolated and washed plasma clot (World Health Organization [WHO] method). All three methods quantified functional thrombin-coagulable fibrinogen. Plasma specimens were obtained from three groups of patients: those with liver disease and those taking either coumarin derivative or heparin. In all of these conditions, there are deviations from the normal process of fibrin clot formation. The KFA method yielded results that were consistent and provided excellent precision and accuracy allowing quantification of plasma fibrinogen in the range of 70-800 mg/dL (2-23.5 microM). The determination of fibrinogen by the KFA method was not adversely affected using plasma from patients treated with heparin and those undergoing coumarin therapy. Statistical analysis of the results indicated that the KFA method compared very favorably with the von Clauss and WHO methods. In assessing the clinical utility of each method, the WHO method was found to be labor intensive and time consuming; therefore, not suitable for routine use in a clinical laboratory. The von Clauss method required a trained laboratory technician and some laboratory manipulations. The KFA method was not only reliable and accurate, but also fully automated, making it the easiest and the fastest to perform routinely.