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Factor VIII Activity, Clotting
Test Code30816
CPT Codes
85240<br>Limited Access Code
Preferred Specimen
1 mL platelet-poor plasma collected in 3.2% sodium citrate (light blue-top) tube
Minimum Volume
0.5 mL
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.
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.
Transport Container
Plastic vial
Transport Temperature
Frozen
Specimen Stability
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen -20°C: 14 days
Frozen -70°C: 1 year
Refrigerated: Unacceptable
Frozen -20°C: 14 days
Frozen -70°C: 1 year
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Hemolysis; received room temperature; received refrigerated; received thawed
Methodology
Clot Detection
Setup Schedule
Set up: Mon-Fri; Report available: Next day
Reference Range
See Laboratory Report
Clinical Significance
The most common form of hemophilia, Hemophilia A, is caused by a deficiency of Factor VIII. Hemophilia A is an X-linked disorder affecting between 1 in 5000 to 10000 males. Measurement of Factor VIII activity level is used to classify Hemophilia A (mild, moderate or severe) and to assess response to treatment.
Note: for patients receiving Hemilbra (aka emicizumab), the Factor VIII activity clotting method is not recommended. Hemilbra will cause falsely elevated Factor VIII activity values. A chromogenic Factor VIII Activity method is recommended.
Note: for patients receiving Hemilbra (aka emicizumab), the Factor VIII activity clotting method is not recommended. Hemilbra will cause falsely elevated Factor VIII activity values. A chromogenic Factor VIII Activity method is recommended.
