Screening of dysfibrinogenaemia using the fibrinogen function versus antigen concentration ratio

The diagnosis of inherited and acquired dysfibrinogenaemia is usually suspected in patients with otherwise unexplained prolonged thrombin time or other tests with thrombin-like enzymes (1). Confirmation of the diagnosis requires discordant results from the investigation of functional fibrinogen and its antigen concentration. However, the issue of the difference between the two results required to confirm dysfibrinogenaemia has rarely been addressed. A difference of at least 0.5 g/l between functional fibrinogen using the method of Clauss and heat precipitation method according to Schulz has been suggested as a prerequisite (1). In the case of acquired dysfibrinogenaemia with an underlying liver disease the discordance should reach at least 1.0 g/l (2). Rodgers and Garr (3) suggested to establish a ratio between fibrinogen function and antigen concentration. In that study plasma from healthy blood donors was investigated using the Clauss method and radial immunodiffusion. We applied this approach to randomly selected patients at the time of admission to a University Hospital Department. Since fibrinogen is one of the major acute phase proteins, the determination of the C-reactive protein (CRP) was included for comparison.