von Willebrand Factor Antigen, Plasma
Use
The von Willebrand Factor Antigen test is crucial for diagnosing von Willebrand disease (VWD) and distinguishing between its subtypes alongside the ristocetin cofactor activity and factor VIII coagulant activity assays. It also assists in differentiating VWD from hemophilia A and monitors the effectiveness of von Willebrand factor concentrates and DDAVP treatments in VWD patients.
Special Instructions
For optimum results, this test should be used with von Willebrand factor ristocetin cofactor activity and factor VIII coagulant activity tests. For a comprehensive diagnostic approach, considering a panel of tests with reflexive testing and interpretive reporting is recommended. Each coagulation assay requested should be in its own vial, and it's crucial to follow proper specimen handling and processing guidelines to prevent platelet contamination.
Limitations
Lipemic specimens can lead to underestimation, and rheumatoid factor can cause overestimation of von Willebrand Factor levels. Being an acute-phase reactant, von Willebrand Factor levels can naturally be elevated due to conditions like inflammation, stress, and pregnancy, which may complicate diagnosing mild forms of VWD. Hence, normal low levels don't rule out VWD, especially for blood group 'O' individuals. Proper handling and repeat testing are advised when necessary.
New York Approved
Methodology
Immunoassay (Latex 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
0.5 mL
Container
Plastic vial
Collection Instructions
Centrifuge, transfer all plasma into a plastic vial, centrifuge again, aliquot plasma into a plastic vial, and freeze immediately.
Storage Instructions
Freeze plasma immediately at -20 degrees C or ideally at ≤ -40 degrees C.
Causes for Rejection
Gross hemolysis, lipemia, or icterus.
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |