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VWF:CB and VWF:RCo. Assay to differentiate between type 1 and type 2 von Willebrand disease in national blood centre

Abstract number: PP-MO-636

Afandi¹ F.M.D., Che Nordin¹ S., Abd Karim¹ F., Ayob¹ Y., Asidin¹ N.

¹¹Haemostasis, National Blood Centre, Kuala Lumpur, Malaysia

How-to-cite Afandi FMD, Che Nordin S, Abd Karim F, Ayob Y, Asidin N. VWF:CB and VWF:RCo. Assay to differentiate between type 1 and type 2 von Willebrand disease in national blood centre. Journal of Thrombosis and Haemostasis 2009; Volume 7, Supplement 2: Abstract PP-MO-636

VWD is the most common hereditary disorder due to either a qualitative or a quantitative defect in VWF. VWF is a multimeric plasma protein that plays an important role in primary haemostasis,by sustaining indirect platelet adhesion especially at high shear stress and in secondary haemostasis by protecting FVIII from degradation.In order to provide proper clinical management,accurate identification of the different subtypes is essential. The goal standard of the differentiating diagnosis of different types of VWD is the multimeric assay however this test is not available in most diagnostics laboratory. Haemostasis National Blood Centre has been relying on estimation of VWFAg,VWFCB and platelet aggregation for the identification of VWD.Despite the high interlaboratory and intralaboratory variability in VWFRCo, there are studies show it can contribute towards the diagnosis of VWD. The purpose of this study is to evaluate the value of adding VWFRCo in the diagnosis of type 1 and type 2 VWD.50 patients undergoing screening for VWD from June 2008 to October 2008 were selected and their samples were tested for Basic Coagulation, Platelet Aggregation, FVIII, VWFAg, VWFCB and VWFRCo. The VWFCB was measured by ELISA method. VWFRCo was measured using agglutination test. Samples that were below the diagnostic threshold (50 IU/dL)in VWFRCo were repeated to ensure the consistency of the assay. Of 50,18 patients were normal for all assay.The ratios of both VWFAg to VWF:CB and VWFAg to VWFRCo were around 1.12 patients were classified as type 1 with ratios of both VWFAg to VWFCB and VWFAg to VWFRCo were below 2.17 patients were classified as type 2 with ratios of VWFAg to VWFRCo were above 2 however the ratios of VWFAg to VWFCB were below 2.3 patients were classified as type 3 with all three assays lower than 5 IU/dL. We were able to demonstrate that VWFRCo assay can improve the pick up rate of type 2 VWD despite its high interlaboratory and intralaboratory variability.Both VWFCB and VWFRCo assay allow the discrimination of type 1 and type 2 VWD.It is hoped that in the future there would be better VWFRCo assay that can improve the diagnosis of VWD and therefore contribute towards better management of this disease.

Disclosure of interest: none declared.

To cite this abstract use the following format:

Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2: abstract number

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