von Willebrand Factor Antigen


Sunquest Code:VWA  
Epic Code:LAB757Epic Name:von Willebrand Antigen
Synonyms:von Willebrand Antigen; VWF Antigen
Methodology:Latex immusorbant assay (LIA)
CPT Code:85246
Turnaround Time:Specimen is accepted and processed 24 hours/day. Test is performed 1-3 times/week; results are reported within 2-7 days. Available stat if urgent
Special Instructions:Usually performed as part of a von Willebrand screen or panel with Factor 8 activity and a test of von Willebrand factor activity such as von Willebrand's factor activity or Ristocetin Cofactor Activity.
Associated Links:

Specimen Collection and Processing for Coagulation Specimens, von Willebrand Factor (VWF) Panel Algorithm, von Willebrand Factor (VWF) Screen Algorithm



Collection Instructions

Specimen:Blood
Optimal Volume:2.7 mL (in 3 mL tube) - filled to fill line on the tube.
Minimum\Peds Volume:2.7 mL (in 3 mL tube) - filled to fill line on the tube. If part of a von Willebrand panel, collect TWO tubes.
Collection Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Causes for Rejection:Underfilled tube or clotted specimens.


Processing and Shipping

Specimen Processing:See link to Specimen Collection and Processing for Coagulation Specimens.
Shipping Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Test Performed at or Referral Lab Special Coagulation  (UMMC-East Bank)


Interpretive

Critical Range:Less than 10%
Reference Range:

1-4 d

50-287%

5-29 d

50-254%

30-89 d

50-246%

90-179 d

50-206%

180-364 d

50-197%

1 y and older

50-200%

Age specific reference ranges have not been established for patients less than 1 day old.

 

Use:The von Willebrand factor protein is a large glycoprotein which functions in hemostasis by mediating adhesion of platelets to exposed subendothelium. It also forms a complex with Factor 8, thus stabilizing and protecting it from rapid removal from the circulation. There are a multitude of mutations of this molecule that can occur, resulting in the heterogeneous disorder called "von Willebrand's Disease". This disease is characterized by predominately mucous membrane hemorrhage (epistaxis, gastrointestinal, menorrhagia) of varying severity occurring in both males and females. The von Willebrand Antigen assay measures the amount of the von Willebrand protein produced. The presence of Rheumatoid Factor may produce an overestimation of the von Willebrand antigen.


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