Comparison of different methods to measure fibrinogen concentration in canine plasma with respect to their sensitivity towards the fibrinogen degradation products X, Y and D.

In this study, fibrinogen measurements according to the Clauss method, photometric method and Jacobsson method have been investigated to find out how they are influenced by adding in vitro the purified canine fibrinogen degradation products (FDP) X, Y and D. Test results according to the Clauss method were found to be underestimated if the fragments X, Y and D were added while measurements according to the Jacobsson method turned out to underestimate the real fibrinogen concentration if the FDP Y and D were added. The Clauss method was particularly sensitive towards FDP. Results were considerably underestimated even with a quantity as little as 0.05 g FDP Y or FDP D/g fibrinogen (p < 0.05). The photometric method was only affected by FDP X leading to false high results. If FDP X was added, fibrinogen values were also overestimated with the Jacobsson method. Our results demonstrate that the photometric method is the most accurate.