Laboratory Services

Von Willebrand Factor Activity

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Updated Test Information:

Test Description
Von Willebrand Factor Activity
Synonym(s)

Ristocetin Cofactor Alternative, VWF Activity, UOW843

Test ID
VWFACT
General Information

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.

Container Type

3 mL or 5 mL Light Blue Citrate Tube

Specimen Type

Plasma

Specimen Requirements

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

Specimen Collection / Processing Instructions

MUST PROCESS WITHIN 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

Minimum Sample Volume

1 mL

Stability

Frozen

Limitations

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.

Department (code)

Coagulation

Methodology

Innovance VWF:GPIbM Latex-Immunoassay

Testing Schedule

Tuesday

CPT Code(s)

85245

Reference Range

Units: %


Male/Female


50-200


Effective date: 10/03/2006

Performing Lab

UW

LOINC Code(s)