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von Willebrand Screen : 90271
MessageThe aliquot must remain frozen. Freeze thaw cycle will adversely affect specimen integrity. CRITICAL FROZEN: Separate specimens must be submitted when multiple tests are ordered.
Test Code
VWDS or 90271
Alias/See Also
Factor VIII Functional,Procoagulant Factor 8,Antihemophilic Factor,RcoF,von Willebrand Factor Activity,Hemophilia A,Hemophiliac Factor
CPT Codes
85240, 85245, 85246, 85730
Includes
Panel includes: von Willebrand Factor Antigen, Ristocetin Cofactor Activity, Factor VIII Activity, Activated Partial Thromboplastin Time
Instructions
Platelet-poor plasma: Centrifuge light blue-top tube for 15 minutes at approximately 1500 g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Plasma must be free of platelets (<10,000/mcL). Freeze immediately and ship on dry ice.
Note: Storage of whole blood at refrigerated temperatures prior to processing may lead to cryoprecipitate formation and falsely low Factor VIII and von Willebrand Factor studies.
Note: Storage of whole blood at refrigerated temperatures prior to processing may lead to cryoprecipitate formation and falsely low Factor VIII and von Willebrand Factor studies.
Transport Container
Preferred Specimen
3 mL frozen platelet-poor plasma collected in 3.2% sodium citrate (light blue-top) tube
3 mL frozen platelet-poor plasma collected in 3.2% sodium citrate (light blue-top) tube
Transport Temperature
Frozen.
Specimen Stability
Room temperature: Unacceptable; Refrigerated: Unacceptable; Frozen: 14 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Hemolysis; Lipemia; Thawed plasma received room temperature or refrigerated; Received room temperature; Received refrigerated; Received thawed
Methodology
Immunoturbidimetric, Agglutination, Clotting
Setup Schedule
Monday, Wednesday, Friday
Report Available
1-4 days
Reference Range
Factor VIII Activity: 50-180% normal
Ristocetin Cofactor Activity: 42-200% normal
Von Willebrand Factor Antigen: 50-217%
Partial Thromboplastin Time, Activated:
≤6 months Not established
>6 months 23-32 sec
Flagging not provided. Pediatric reference intervals have not been established. Based on published literature, the adult reference interval (23-32 seconds) is generally applicable down to approximately 6 months of age with younger patients having a slightly higher upper limit by several seconds.
Ristocetin Cofactor Activity: 42-200% normal
Von Willebrand Factor Antigen: 50-217%
Partial Thromboplastin Time, Activated:
≤6 months Not established
>6 months 23-32 sec
Flagging not provided. Pediatric reference intervals have not been established. Based on published literature, the adult reference interval (23-32 seconds) is generally applicable down to approximately 6 months of age with younger patients having a slightly higher upper limit by several seconds.
Clinical Significance
This test may be used for initial evaluation of individuals with clinical suspicion of von Willebrand disease (VWD).
von Willebrand factor (VWF) is a blood coagulation protein that has 2 functions: (1) mediating platelet adhesion to the injured endothelium and (2) acting as a protective carrier protein for coagulation factor VIII. Deficiency of VWF causes VWD, the most common inherited bleeding disorder that affects approximately 1 in 1,000 individuals at the primary care level [1]. VWD is classified into type 1 (quantitative deficiency of VWF), type 2 (qualitative deficiency of VWF), and type 3 (total absence of VWF). Different types of VWD are further categorized into subtypes, identification of which is important to inform prognosis and treatment decisions.
von Willebrand factor (VWF) is a blood coagulation protein that has 2 functions: (1) mediating platelet adhesion to the injured endothelium and (2) acting as a protective carrier protein for coagulation factor VIII. Deficiency of VWF causes VWD, the most common inherited bleeding disorder that affects approximately 1 in 1,000 individuals at the primary care level [1]. VWD is classified into type 1 (quantitative deficiency of VWF), type 2 (qualitative deficiency of VWF), and type 3 (total absence of VWF). Different types of VWD are further categorized into subtypes, identification of which is important to inform prognosis and treatment decisions.
Performing Laboratory
med fusion
