Test Directory

Test Code
VWFA
Test Name
von Willebrand Factor Activity
CPT Codes
85245
Expected Turnaround Time
2 - 4 days
Clinical Utility

Screen and diagnose von Willebrand factor (vWF) deficiency.

Specimen and Container Info

Specimen Type: Plasma  

Collection Container: 1 Full Light Blue Top (Sodium Citrate) 

Collection Instructions

Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.

Processing and Submission Instructions
Patient Preparation
Testing is contradictory for patients on anticoagulant therapy.
Transport Instructions

Transport to the laboratory frozen. 

Stability Requirements

Frozen

Platelet poor plasma: 14 days 

Causes for Rejection
  • Platelet poor plasma thawed in transit
  • Specimens past stability
Methodology
Immuno Turbidometric
Reference Intervals
SexAgeReference IntervalUnit
FemaleAll Age Groups50-150%
MaleAll Age Groups50-150%
Performing Location
Roble Road Core Laboratory
Alternate Names
  • VWF Activity
  • Ristocetin Cofactor
Testing Schedule
Routine, 3 times per week