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VonWillebrand Antigen
MessagePerforming Lab: Regions
Test Code
3528
Alias/See Also
Sunquest: VWBAG, Factor 8/Factor 8 Related Antigen
CPT Codes
85246
Preferred Specimen
2.7 mL (in 3 mL tube) 3.2% Sodium Citrate Plasma (light blue-top) tube filled to fill line on the tube
Minimum Volume
1.0 mL plasma aliquot per test
Other Acceptable Specimens
1.0 mL platelet poor plasma (frozen)
Instructions
Processing: Freeze an aliquot of platelet poor plasma at -20C if not performed within 4 hours of collection
Centrifuge light blue-top tube for 15 minutes at approximately 1500 g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet poor plasma into a new plastic vial. Plasma must be free of platelets (<10,000/mcl). Freeze immediately and ship on dry ice.
Centrifuge light blue-top tube for 15 minutes at approximately 1500 g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet poor plasma into a new plastic vial. Plasma must be free of platelets (<10,000/mcl). Freeze immediately and ship on dry ice.
Transport Container
Transport processed samples frozen on Dry Ice
Transport Temperature
Frozen if > 4 hours old
Specimen Stability
Room Temperature: 4 hours Refrigerated: 4 hours Frozen 72 hours at -20C or 2 weeks at -80C
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Refrigerated or Room temperature >4 hours
Methodology
Immuno-turbidimetric
Setup Schedule
Monday, Wednesday, Friday
Report Available
3 business days
Reference Range
50-160%
Clinical Significance
The von Willebrand molecule is a large glycoprotein which functions in hemostasis by mediating adhesion of platelets to exposed subendothelium. It also forms a complex with Factor 8, thus stabilizing and protecting it from rapid removal from the circulation. There are a multitude of mutations of this molecule that can occur, resulting in the heterogeneous disorder called "von Willebrand's Disease". This disease is characterized by predominately mucous membrane hemorrhage (epistaxis, gastrointestinal, menorrhagia) of varying severity occurring in both males and females. The von Willebrand Antigen assay measures the amount of the von Willebrand molecule produced.
