von Willebrand Factor (vWF) Antigen

Casandra

Casandra Test Code LC23840Version 1 (DRAFT)

Performing Lab

Lab LabcorpLab Test ID 086280CPT Code 85246

von Willebrand Factor (vWF) Antigen

Also known as: Antigenic Factor VIII, CRM Assay, vWF Antigen

Clinical Use

Order Test

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.

Test Details

Methodology

Immunoassay (LIA)

Biomarkers

von Willebrand Factor

Protein

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

LOINC Codes

Order Codes

27816-8

Result Codes

27816-8

Result Turnaround Time

1-3 days

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.