Factor VIII vWF Protein
Aliases
Von Willebrand Antigen Factor Assay
Useful For
von Willebrand disease (vWD)is the most common inherited bleeding disorder. Clinically, it is often characterized by mucocutaneous hemorrhages. The three principle types of vWD are:
Type 1 corresponds to a quantitative deficiency of vWF
Type 2 refers to a qualitative deficiency of vWF
Type 3 is characterized by a total absence of vWF
Patient Preparation
No special patient preparation required
Special Collection Instructions
Properly filled 9:1 ratio (blood to anticoagulant); 3.2% NaCitrate tube
Collection Method
Venous Draw; properly filled 9:1 ratio (blood to anticoagulant)
Minimum Volume
0.5 mL of plasma from a properly filled 1.8 mL or 2.7 mL NaCitrate (light blue) tube
Container
Light Blue Sodium Citrate
Preferred Specimen
2.7mL Lt. Blue (3.2% NaCitrate)
Acceptable Specimens
1.8 mL Lt. Blue (3.2% NaCitrate) tube
Reference or Target Ranges
46-180%
Reportable Units
% (percentage)
Critical Value
Not defined for this assay
Reasons for Rejection
Hemolysis Threshold | N/A |
Icterus Threshold | N/A |
Lipemia Threshold | N/A |
Interfering Subtances/Other | Short draws, over draws, clotted, improperly labeled, hemolyzed, lipemic or icteric samples, samples > 4 hours from collection |
Specimen Stability
Ambient | Plasma – 4 hours |
Refrigerated (4°C to 8°C) | N/A |
Frozen(-70°C to -20°C) | 2 weeks@ -20°C; 1 year @ -70°C |
Performance Information
Days and Time Performed | Batched daily Monday-Friday unless STAT |
Expected Turn Around Time | Batched Monday – Friday |
Stat Availability | Yes |
Performing Bench | Coagulation |
Methodology/Method Description | Stago Compact – Immuno-turbidimetric determination |
Special Handling
Centrifugation: 5 minutes at 5000 rpm. Plasma must be centrifuged twice
(double spun) to remove platelets. (<10,000 mm3)
Additional Information/Important Notes
After being spun down twice, separate plasma into 2 aliquot tubes and transport to University Hospital Laboratory frozen on dry ice.
CPT Codes
85246