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VonWillebrand Factor Activity
MessagePerforming Lab: Regions
Test Code
3529
Alias/See Also
Sunquest: VWBF
CPT Codes
85397
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
55-200%
Clinical Significance
The diagnosis of von Willebrand Disease (VWD) requires a number of special tests. The measurement and comparison of von Willebrand Factor Antigen (VWF:Ag), VWF Activity and Factor VIII (FVIII) levels in plasma aid in the differentiation of quantitative defects (Type 1 or 3) or qualitative defect (Type 2).
