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Factor VIII Activity, Clotting : 347
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
F8ACT or 347
Alias/See Also
Hemophilia A,Procoagulant Factor 8,Hemophiliac Factor,Antihemophilic Factor,Factor VIII Functional
CPT Codes
85240
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
1 mL frozen platelet-poor plasma collected in 3.2% sodium citrate (light blue-top) tube
Minimum Volume
0.5 mL
1 mL frozen platelet-poor plasma collected in 3.2% sodium citrate (light blue-top) tube
Minimum Volume
0.5 mL
Transport Temperature
Frozen.
Specimen Stability
Room temperature: Unacceptable; Refrigerated: Unacceptable; Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Hemolysis; Received thawed
Methodology
Clotting
Setup Schedule
Monday - Saturday
Report Available
1-4 days
Reference Range
50-180% normal
Clinical Significance
This test is useful to evaluate a prolonged aPTT. The most common form of hemophilia is caused by a deficiency of Factor VIII. Hemophilia A is an X-linked disorder affecting between 1 in 5,000 to 10,000 males. Borderline low Factor VIII activity can be seen in female carriers of the defective Factor VIII gene. Typically this test is combined with other screening tests (eg. von Willebrand factor, Ristocetin Cofactor Activity) to evaluate for the presence von Willebrand disease.
Performing Laboratory
med fusion