von Willebrand factor antigen (VWF:Ag)
Concentration of VWF irrespective of function is ascertained with a latex immunoassay which employs latex particles coated with antibodies to VWF to capture VWF in the test plasma. The VWF acts as a bridge between latex particles that leads to a degree of agglutination directly proportional to VWF concentration, which is measured turbidimetrically.
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.
Blood group O 50 - 124
Non-O blood groups 67 - 172
350µL 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