von Willebrand Factor Activity, Plasma

Casandra

Casandra Test Code MC55170Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID VWACTCPT Code 85397

von Willebrand Factor Activity, Plasma

Clinical Use

Use

This test is used for the diagnosis of von Willebrand disease (VWD) and distinguishing between VWD subtypes or from hemophilia A. It is also important for monitoring the therapeutic efficacy of treatment with DDAVP (desmopressin) or VWF concentrates in patients with VWD.

Special Instructions

The test is most effective when combined with the measurement of von Willebrand factor antigen and factor VIII coagulant activity. Ideally, it should be performed as part of a panel of tests with reflexive testing and interpretive reporting.

Limitations

The measurement of von Willebrand factor (VWF) activity alone has limited diagnostic value. The diagnosis of VWD requires comprehensive clinical and laboratory evaluation. Assay results must be integrated with assays of VWF antigen and factor VIII coagulant activity for optimal clinical utility and diagnostic efficiency. Certain factors like high triglycerides, hemoglobin, or bilirubin levels can affect the test results, and the presence of human antimouse antibodies may cause interference in immunoassays.

Test Details

New York Approved

Methodology

Immunoassay (Latex Immunoassay)

Biomarkers

von Willebrand Factor

Protein

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Order Codes

68324-3

Result Codes

68324-3

Result Turnaround Time

1-3 days

Specimen

Plasma

Volume

2 mL in 2 vials each containing 1 mL

Minimum Volume

0.5 mL

Container

Light-blue top (3.2% sodium citrate); Submission Container/Tube: Plastic vial (polypropylene preferred)

Collection Instructions

Specimen must be collected prior to factor replacement therapy. Centrifuge, transfer all plasma into a polypropylene vial, and centrifuge plasma again. Aliquot plasma (1-2 mL per aliquot) into 2 separate polypropylene vials leaving 0.25 mL in the bottom of centrifuged vial. Freeze plasma immediately at -20 degrees C or, ideally, <=-40 degrees C. Send specimens in the same shipping container. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.