VWF Activity (VWACT) | | | |
EPIC Test Name
VON WILLEBRAND PANELEPIC Code
LAB1112Specimen Requirements
Plasma |
---|
Minimum Volume: | 2.7 mL |
Collection: | Collect using standard laboratory procedures. Tubes must be full to obtain proper blood to anticoagulant ratio or the specimen will be rejected. |
Transport: | Specimens scheduled to arrive in lab in less than 4 hours can be sent at room temperature. Specimens arriving more than 4 hours must be platelet poor specimens and need to be frozen before transport. Place in an insulated container filled with dry ice to ensure that the specimen does not thaw. |
Stability: | Room temp: 4 hours Frozen: 2 weeks at -20 C 6 months at -70 C. |
Container: | Light-blue top (3.2% sodium citrate) |
Processing/Storage: | Specimens that cannot reach the lab within the time frame should be double spun at 2500 g for 15 minutes to obtain platelet poor plasma. 0.5mL aliquots should be frozen in plastic at -20 degrees C. |
Rejection Causes: | Clotted
Insufficent Sample Volume |
Methods
Immuno-turbidimetricTurnaround Time
Specimen | Turnaround Time |
---|
Plasma | Testing is batched |
Reference Ranges
Immuno-turbidimetric
All Range | Unit |
---|
55-150 U/dL | U/dL |
Clinical Indications
Diagnosis of von Willebrand disease and acquired von Willebrand syndrome. For diagnosis, it is best if ordered with von Willebrand Factor Antigen and Factor VIII activity. This assay measures the platelet-binding activity of vWF and replaces the older ristocetin cofactor assay as a functional test. If vWF activity is decreased, vWF ristocetin cofactor assay (send-out test) could also be ordered. vWF is elevated in acute phase reaction. The test should be ordered when the patient is at a baseline state of health to avoid false negative results.Common Synonyms
Von Willebrand Factor ActivityContact Information
Special Testing: (315)464-4460