von Willebrand Factor (vWF) Antigen
Also known as: Antigenic Factor VIII, CRM Assay, vWF Antigen
Use
Diagnose von Willebrand factor (vWF) deficiency6,8-10
Special Instructions
If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted. Refer to Coagulation Collection Procedures for directions. Avoid warfarin (Coumadin®) therapy for two weeks and heparin therapy for two days prior to the test. Do not draw from an arm with a heparin lock or heparinized catheter.
Limitations
A number of transient clinical conditions can raise vWF levels into the normal range even in individuals with congenital deficiencies. vWF is an acute phase reactant with levels influenced by stress, inflammation, acute infection, physical exercise, surgery, estrogen administration, and pregnancy. Individuals with type O blood tend to have approximately 30% lower vWF levels compared to other blood types.
Methodology
Immunoassay (LIA)
Biomarkers
LOINC Codes
- 27816-8
- 27816-8
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
Not provided
Container
Blue-top (sodium citrate) tube
Collection Instructions
Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Evacuated collection tubes must be filled to ensure a proper blood-to-anticoagulant ratio. Mix immediately by gentle inversion at least six times. A discard tube is not required unless using a winged collection set. In that case, use a discard tube to prevent under-filling. Collect noncitrate tubes first, followed by citrate tubes.
Patient Preparation
Avoid warfarin (Coumadin®) therapy for two weeks and heparin therapy for two days prior. Do not draw from an arm with a heparin lock.
Storage Instructions
Freeze.
Causes for Rejection
Gross hemolysis; clotted specimen; frozen specimen thawed in transit; improper labeling
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 28 days |