Veripath Test Directory

Synonyms Factor VIII -related Antigen
Description Von Willebrand Factor is involved in primary hemostasis by binding to platelets via specific receptor glycoprotein Ib and acts as an adhesive bridge between the platelets and subendothelium at the site of vessel injury. In addition, vWF serves as a carrier for Factor VIII (antihemophilic Factor A) and protects it from degradation. Von Willebrand disease is the most common inheritable bleeding disorder, manifesting as muco-cutaneous type of bleeding.
The Von Willebrand Factor Antigen is a latex particle enhanced immunoturbidimetric assay to quantify VWF:Ag in plasma.
Specimen Requirements 
Container Light blue (3.2 % sodium citrate) collection tube
Specimen Type Blood
Preferred Collection Volume 3 mL
Minimum Collection Volume Adult: 2 mL, Neonates : 2 mL
Collection Instructions When drawing specimens for coagulation testing, always draw a "pilot" tube (7-10ml plain red top tube), completely filled. This removes tissue fluid contamination. Samples should be obtained from peripheral vein whenever possible. If drawn from indwelling catheter, the line should be flushed with 15mL of saline. After irrigation, a "pilot" tube should be drawn and discarded.
Specimen Handling In-house patients, transport at room temperature.
Out-side client, follow collection instructions and the steps below:
1. Spin light blue top tube. Remove plasma avoiding platelet/buffy coat layer. Spin plasma again to remove top portion of plasma ans place 1mL of PLATELET-POOR PLASMA in plastic tube. (Glass tube unacceptable). Double-centrifugation is critical for accurate results as platelet contamination may cause erroneous results.
2. Plasma must be frozen within 4 hours of collection. CRITICAL WARNING: Specimens must remain frozen until ready to test. Submit separate aliquots when multiple tests are ordered on the same patient specimen.
Rejection Criteria Hemolysis, clotted, short sample, >4 hrs old (if not frozen), thawed plasma, heparin contamination.
Methodology Immunoturbidimetry
Reference Range 50 - 150 %
CPT Code(s) 85246
Department Hemostasis/Coagulation
Contact Information Hemostasis Lab; 214-633-4959 Customer Service: 214-633-0400, Toll Free 1-877-887-8136.
Turn Around Time3-5 days
Performed Friday, Monday
Performed by Hemostasis Lab
Updated/Reviewed 07/25/2016