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Test Code VWF Ag Von Willebrand Antigen

Clinical System Name

Von Willebrand Antigen

Synonyms

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

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

Preferred Vol :1.8 mL

Minimum Vol: N

 

Note: 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 trasferred 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

 

Reject due to: Clotted, Hemolyzed, Insufficient quantity, and  Improper collection.

Spin: N

Aliquot: N

Temp: RT

Storage location: Core 6 Freezer  ( -70 C).

 

Note: Deliver blood to Core Coag bench.  Coag Technologist will process. 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 fill line. 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 trasferred 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 2 aliquots of 1.0 mL plasma in plastic tubes at -70C.

Ship frozen on dry ice.

.

Stability

Specimen Type Temperature Time
Citrated platelet-poor plasma Room temp N
  Refrigerated N
  Frozen   -20C or -70 3 m

 

Availability

STAT Performed TAT
Y Daily 1 h

 

Performing Laboratory

Seattle Children's Laboratory    

 

Department

Department:  Coagulation

Phone Number: 206 987-2578

 

 

 

Reference Range

50 - 200%

 

 

Methodology

Method:  Immuno-Turbidimetric Assay  by STA® Compact  Analyzers

Analytical Volume: 1.0 mL  plasma

This is enough for a PT, PTT, TT, 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.

CPT Codes

85246

Critical Values

Not defined for this test.