Laboratory Medicine Program
von Willebrand Factor (vWF) Complex
(vWF Profile/Panel)
Clinical Decription:
von Willebrand factor (vWF) complex includes factor VIII activity, vWF activity and vWF antigen. vWF is a large multimeric hemostastic protein synthesized in the endothelial cells and released into the vascular space. It has multiple functions including carrier protein for factor VIII, platelet agglutination and high shear platelet-surface adhesion. The vWF complex is assessed in three components: factor VIII activity, vWF activity (ristocetin cofactor activity) and vWF antigen. The diagnosis and characterization of von Willebrand's disease includes a bleeding time, vWF complex study and vWF multimer studies.
<br/><em>Holmberg, L, Berntorp E, Donner M et al. Von Willebrands?s disease characterized by increased ristocetin sensitivity and the presence of all von Willebrand factor multimers in plasma Blood 1986: 68(3) ; 668-672.</em>
Method: Latex immunoturbidimetric Assay; Siemens Sysmex CS-5100
Component Tests Used: Factor VIII, vWF Activity, vWF Antigen
Reference Ranges Used:
F VIII Activity 0..64 - 1.76 IU/mL | vWF Activity 0.40 - 1.50 IU/mL | vWF Antigen 0.55 - 1.81 IU/mL
Specimen Type: Citrated plasma
Collected In: 3.2% Sodium Citrate
Volume: 2 x 1.0 mL (minimum: 2 x 1.0 mL)
Shipping: Send frozen on dry ice.
Special Instructions: Patient should be fasting, if possible. The specimen must be double-centrifuged to obtain a platelet-poor plasma specimen (Plt <10x10E9/L): 1. Immediately centrifuge specimen at 1500xG for 10 minutes. 2. Separate the plasma from the platelet/buffy coat and transfer into a clean plastic tube. 3. Centrifuge the separated plasma at 1500xG for 10 minutes. 4. Transfer 1.0 to 2.0 mL of the double-centrifuged plasma into a clean plastic tube, leaving approx. 200 uL for discard. 5. Freeze plasma aliquot immediately for storage. Maintain frozen for shipping and handling.
Testing Schedule(s): Weekly.
Turnaround Time: 5 days
For more information, call 416.340.5227 or 1.866.865.5227