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HelpTest Code LAB757 Von Willebrand Antigen
Clinical System Name
Von Willebrand Antigen
Description
Von Willebrand disease (vWD), the most common hereditary bleeding disorder, is caused by a quantitative deficiency (Type 1 and Type 3) or a qualitative dysfunction (Type 2) of vWF. The principal clinical manifestations of vWD are excessive and prolonged bleeding after surgery and mucosal hemorrhages such as epistaxis and menorrhagia. vWF antigen assay determines the quantity of vWF protein but does not measure the qualitative function of the vWF.
Sample Requirements
Specimen: Whole Blood
Container(s): Lt Blue/Citrate
Required Vol: (1) 1.8 mL or (1) 2.7 mL
Minimum Vol: N
Note: This is enough for a PT, PTT, TT, Fibrinogen, and vWF Ag to be run on the same sample.
Preferred method of collection is venipuncture with vacuum fill. Test results are affected by incorrect blood volume. Use of a Vascular Access Device for the collection of coag testing is not recommended. Please review the Coagulation Lab Collection Job Aid for detailed instructions.
Processing Instructions: Main Campus
Deliver whole blood to Coag bench. Coag Technologist will process.
Reject due to: clotted, insufficient quantity (underfill), or improper collection (overfill).
Spin: Y
Aliquot: Y
Storage location: Core 14 Freezer ( -70 C).
Specimen should be centrifuged within one hour of collection. Transfer upper 3/4 layer of plasma to plastic tube affixed with large Epic aliquot label. Do not pool. Assay immediately.
Processing Instructions: Offsite & Regional Clinics
Reject due to: clotted, insufficient quantity (underfill), or improper collection (overfill).
Spin: Y
Aliquot: Y
Storage location: -70 C (preferred) or -20 C.
Specimen should be centrifuged within one hour of collection. Double spin, transfer upper 3/4 layer of plasma to plastic tube affixed with large sample label. Freeze one aliquot of plasma at -70 C (preferred) or -20 C. Preferred plasma volume: 1.0 mL, minimum plasma volume: 0.6 mL. Do not pool.
Non-Children's Hospital Offsite collection: Ship completely frozen on dry ice.
Children's Hospital Regional Clinic collection: Ship completely frozen in frozen Nalgene Labtop cooler with ice pack inside an insulated soft cooler.
Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| Citrated platelet-poor plasma | Room temp | ≤4 h |
| Refrigerated | N | |
| Frozen -20 C or -70 | ≤3 m |
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Coagulation
Phone Number: 206 987-2617 (Client Services)
Synonyms
LAB757
F8 RELAG
F8 Related Antigen
Factor 8 Related Antigen
Factor VIII Related Antigen
Von Willebrand Factor Antigen
Von Willebrand's Antigen
VWF Ag
VWF Antigen
Availability
| STAT | Performed | TAT |
|---|---|---|
| Y | Daily | 1 h |
Methodology
Method: Latex-binding immunoturbidimetric assay by STA-R MAX
Analytical Volume: 200 uL plasma
Limitations: Method is affected by moderate lipemia, moderate hemolysis, moderate icterus, insufficient quantity (underfill), improper collection (overfill), improper processing, and improper storage. High hematocrit greater than or equal to 56% requires a citrate adjusted tube.
Reference Range
50 - 200%
CPT Codes
85246
Critical Values
Not defined for this test.