Von Willebrand Factor Activity

Ristocetin Cofactor Alternative, VWF Activity, UOW843

VWF activity is a turbidimetric latex bead-based assay that measures the binding of von Willebrand factor (VWF) to platelet receptor glycoprotein Ib (GPIb) without ristocetin.

The diagnosis or exclusion of any type of von Willebrand disease should never be based solely on the VWF activity result. This test should always be interpreted in conjunction with a group of tests (Factor VIII activity, VWF antigen, collagen binding activity and multimer analysis) in the context of the patient's medical history and clinical presentation. Von Willebrand activity can be used to monitor therapeutic efficacy of treatment with DDAVP (desmopressin) or von Willebrand factor concentrates in patients with von Willebrand disease.

3 mL or 5 mL Light Blue Citrate Tube

Plasma

Sample must be centrifuged, aliquoted and frozen within 4 hours of collection

MUST PROCESS WITH 4 HOURS OF COLLECTION
Platelet poor Coag Citrate Specimen processing:
1. Gently invert tube 2-3 times prior to placing in Centrifuge
2. Centrifuge Citrate whole blood at 4500 rpm for 10 minutes
3. Carefully pipette plasma, avoiding the platelet/buffy coat into a plastic vial
4. Centrifuge plasma at 4500 rpm for 10 minutes
5. Pipette the plasma to a plastic vial, leaving the bottom 0.25 mL undisturbed
6. Freeze plasma immediately and transport frozen

1 mL

Frozen

The presence of rheumatoid factor or human anti-mouse antibody (HAMA) may give a falsely elevated (observed more often) or depressed result.

This assay is not affected by unconjugated bilirubin up to 60 mg/dL, conjugated bilirubin up to 40 mg/dL, triglycerides up to 726 mg/dL and rheumatoid factor up to 438 IU/mL.

Coagulation

Innovance VWF:GPIbM Latex-Immunoassay

Tuesday

85245

Units: %

Male/Female

50-200

Effective date: 10/03/2006

UW

68324-3