von Willebrand Factor Antigen


Abbrev Code:VWA   
Order Code:LAB757Order Name:von Willebrand Antigen
Synonyms:von Willebrand Antigen; VWF Antigen
Methodology:Latex immunosorbent assay (LIA)
CPT Codes: 85246 x1, 85246 x1
Turnaround Time:5 days, testing performed 2-3 day per week. With pre-notification, STATs are done within 1 hour after receipt in the testing laboratory.
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.
Container:Blue Na Citrate, 3.2% - fill to fill line on tube
Collection Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Causes for Rejection:Underfilled tubes, overfilled tubes, clotted specimens, not received or processed and frozen within 4 hours of collection or, specimen thawed during transit.


Processing and Shipping

Specimen Processing:
  • Process for Platelet Poor Plasma within 4 hours of collection.
  • Aliquot plasma, place clear tape around label, and freeze at -20C or on dry ice within 4 hours of collection.
  • If multiple tests are collected on 1 blue top, split each blue top into 2 aliquots. Minimum 0.5 mL per tube.
  • A maximum of 6 aliquots are needed per collection.
     
See link to Specimen Collection and Processing for Coagulation Specimens.
Shipping Instructions:
  • Ensure specimen is frozen before shipping.
  • Ship on dry ice, sample must remain frozen during shipping.
     
See link to Specimen Collection and Processing for Coagulation Specimens.
Test Performed at or Referral Lab UM Special Coag (K)  (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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