Von Willebrand Factor Ag (VWF)
Department: Coagulation
Test Synonym(s): LAB757, Factor VIII Related Antigen, VWF, VWF Ag
CPT Codes: 85246
Methodology: Immunoturbidimetric
Reference Range: 45 - 160% Normal range is influenced by ABO blood type.
Tube Type: One 2.7mL Light blue top - 3.2% Sodium Citrate
Specimen: Citrated platelet poor plasma - Requires double centrifugation if sending a plasma aliquot. Aliquot(s) must be frozen if not received by lab within 4 hours of collection.
Alternate Specimen: None
Pediatric Requirements: Pediatric: One 2.7mL Light blue top - 3.2% Sodium Citrate. Neonatal: One 1.8mL Light blue top - 3.2% Sodium Citrate.
Volume: 1.0 mL plasma
Minimum Volume: 1.0 mL plasma
Temperature: Room Temperature for Light blue top tube, must be received within 4 hours of draw. Plasma aliquot(s) must be frozen if not received by lab within 4 hours of collection.
Stability: Room temperature: 4 hours, Frozen: -70 C for one month
Reasons for Rejection: Clotted sample, incorrectly filled tubes, incorrect tube type, grossly hemolyzed sample, grossly lipemic sample sent as whole blood >4.0 hours old
Days Performed: Monday - Friday
Times Performed: 8:00 AM - 3:00 PM. Tests requested after hours, on weekends, or holidays have to be approved by the Medical Director or Pathology Resident on call.
TAT: 1 - 3 days
Significance: Cloudy or lipemic plasma as well as the presence of Rheumatoid factor > 70 IU/mL may lead to an over estimation of the VWF level.
Special Instructions: Deliver to lab immediately. Tubes must be filled to indicator line and not clotted. Indwelling lines should be flushed with saline only and 5 mL of blood should be discarded prior to collecting samples for coagulation studies. If sending plasma aliquots, DOUBLE CENTRIFUGE plasma samples to produce platelet poor plasma. Samples received from an outside lab must be aliquoted and frozen. Grossly hemlyzed, icteric or lipemic samples may be rejected. Ordering physician name and telephone contact information MUST accompany the sample and request. Vanderbilt Esoteric Coagulation: 615 875-5633
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