P54

Comparison of two methods for determination of coagulation factor VIII activity

Susanne Samuelsson1,*

1Department of Clinical Chemistry, Special Coagulations Laboratory, Sahlgrenska University Hospital, Gothenburg, Sweden

Introduction: Haemophilia A is a rare bleeding disorder where the patients have partial or total deficiency of factor VIII. Determination of factor VIII activity is necessary in order to provide accurate assessment in the diagnosis of haemophilia A and to interpret the correct severity of the disease.

Objectives: A material of patient plasma was sent to us for determination of factor VIII activity.

Methods: There are two common methods on the market, the one-stage clotting method and the chromogenic substrate method. Discussions have been held to determine which method is the best suited for giving the most accurate factor VIII activity result. It is well known that there are discrepancies between these two methods in some patients concerning the factor VIII activity. In our laboratory we use both methods and our aim with this study was to compare these two methods.

Results: Both methods showed a good and similar linearity and they can both classify severe haemophilia A. The precision near the cut-off for severe haemophilia A is similar in both methods. . However our results showed a discrepancy between the methods in some of the haemophilia A patients according to classifying the severity of the disease. The methods exhibit different sensitivity to certain anticoagulants and lupusanticoagulans.

Conclusion: Our comparison confirms the importance of using both methods to determine FVIII:C.

Keywords: Blood, Method