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HelpTest Code LAB757 Von Willebrand Antigen
Clinical System Name
Von Willebrand Antigen
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
Sample Requirements
Specimen: Whole Blood
Container(s): Lt. Blue/Citrate
Required Vol: one 1.8 mL tube or one 2.7 mL tube (do NOT over or under fill)
Minimum Vol: N
Note: This is enough for a PT, PTT, vWF Ag, and Fibrinogen on the same sample. Preferred method of collection is venipuncture with vacuum fill. Test results are affected by incorrect blood volume, note fill line on tube. Use of a Vascular Access Device for the collection of coag testing is not recommended.
If this method is used it requires a 5 mL waste volume; 3 mL for size 2 French catheter or smaller. Blood must be transferred to the Lt Blue/Citrate tube by use of a blood transfer device to ensure proper fill.
Specimen should be centrifuged within 1 hour of collection.
Processing Instructions
Main Campus CPA: Core Technologist will process specimen. Deliver blood directly to Core Coag bench.
Reject due to: Clotted, Insufficient quantity (underfill), or Improper collection (overfill).
Spin: Y
Aliquot: Y
Storage location: Core 14 Freezer ( -70 C).
Core Technologist: Specimen should be centrifuged within 1 hour of collection. Spin whole blood, remove plasma. Transfer upper 3/4 layer of plasma to plastic tube affixed with large computer label.
Off-site collection: Preferred method of collection is venipuncture with vacuum fill. Test results are affected by incorrect blood volume, note the fill line on the tube. Use of a Vascular Access Device for the collection of coag testing is not recommended. If this method is used it requires a 5 mL waste volume; 3 mL for size 2 French catheter or smaller. Blood must be transferred to the Lt Blue/Citrate tube by use of the blood transfer device.
Specimen should be centrifuged within 1 hour of collection. Double spin, transfer upper 3/4 layer of plasma to plastic tube affixed with large computer label. Freeze until solid one aliquot of 1.0 mL plasma in plastic tube at -70C (preferred) or -20C.
Non-Children's Hospital Off-site collection: Ship completely frozen on dry ice.
Children's Regional Clinics: 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 |
Availability
| STAT | Performed | TAT |
|---|---|---|
| Y | Daily | 1 h |
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Coagulation
Phone Number: 206 987-2617 (Client Services)
CPT Codes
85246
Methodology
Method: Immuno-Turbidimetric Assay by STA-R MAX
Analytical Volume: 1.0 mL plasma
This is enough for a PT, PTT, vWF Ag, and Fibrinogen on the same sample.
Limitations: Results affected by moderate lipemia, moderate icterus, improper collection, processing and storage.
High hematocrit greater than or equal to 56% requires a citrate adjusted tube.
Reference Range
50 - 200%
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.
Critical Values
Not defined for this test.