von Willebrand factor FVIII binding (VWF:FVIIIB)
In the VWF:FVIII binding assay, patient VWF is captured by a VWF antibody bound to microtitre plate wells. Any FVIII that is bound to the VWF is removed with a high concentration of calcium chloride and exogenous recombinant FVIII is added to standardise the amount attempting to bind to test VWF. The VWF will capture FVIII relative to its FVIII binding capacity, the amount of binding being determined by addition of an enzyme-linked FVIII antibody that is reacted with a chromogenic substrate. The intensity of the coloured product of that reaction is directly proportional to the amount of FVIII bound to VWF.
von Willebrand disease (VWD) is the most common hereditary bleeding disorder and the deficiency can be quantitative, involving reduced levels of normally functioning VWF, or qualitative, involving dysfunctional molecules. Laboratory investigation of VWD encompasses a battery of assays that assess different aspects of the molecule which inform sub-classification and clinical management:
VWF:RCo assay measures glycoprotein Ib binding
VWF:Ag assay measures total protein concentration irrespective of function
VWF:CB assay measures collagen binding
VWF:FVIIIB assay measures FVIII binding
Multimer analysis investigates VWF structure
FVIII activity is measured as levels can be reduced due to reduction of its carrier.
500µL x 1 aliquot
Internal requests: please refer to EPR label
The sample should be analysed or manipulated & stored in the laboratory within 4 hours of venepuncture. Please ensure sample tubes are filled exactly to the fill-line as underfilling creates a dilution error and leads to inaccurate results.
North Wing - 4th and 5th Floors
Westminster Bridge Road
London SE1 7EH
Laboratory opening times
Last updated: 09/03/2017