von Willebrand Factor Activity and Antigen

vWF Activity, vWF Antigen(vWF:Ag)
Core Laboratory & Transfusion Medicine
Hematology
Blood
VWFAA

MSH Coagulation requisition form (MS 520)
This test aids to diagnosis of congenital or acquired vWF deficiencies in patients with bleeding disorders or at risk for vWF deficiency.
The VWF plays an important role both in primary hemostasis by the formation of the hemostatic plug, due to its function in platelet adhesion and aggregation, and in the coagulation process by the stabilization of FVIII.
Von Willebrand Disease (VWD) is the most common inherited bleeding disorder. Clinically, it is often characterized by muco-cutaneous hemorrhages.
Plasma (3.2% Na Citrate)
Full draw
Light Blue citrate tube
Collection Containers – Tube Types
Adult: 2.7 mL
Pediatric Micro tube: 1 mL
Send whole blood sample(s) at room temperature as soon as possible.
If specimens cannot be shipped immediately, centrifuge and separate plasma within 1 hour of collection, send frozen plasma on dry ice
8 hrs at Room Temperature, 12 months at -70ºC or below.
Automated Coagulation Analyzer
Test may be requested at any time. Samples are aliquotted and frozen. The assay is run in batches.
Special arrangements made with Lab
1-2 weeks
vWF Activity:
0.44-1.48 U/mL (Blood Group O)
0.51-1.95 U/mL (Other Blood Groups)

vWF Antigen(vWF:Ag):
0.47-1.47 U/mL (Blood Group O)
0.54-1.76 U/mL (Other Blood Groups) In case of discrepancies, always interpret results using reference ranges as stated on laboratory reports and/or electronic patient chart.
416-586-4800 Extension 4688
Must indicate anticoagulant status