Factor VIII Activity

Profile or Test Panel
Method Clottable
Test Information A one-stage intrinsic system clotting assay is used to measure circulating factor VIII levels. Clotting times of dilutions of patient plasma are compared to dilutions of a plasma pool from normal donors, when added to deficient plasma. Levels are reduced by hereditary (Hemophilia A) or acquired factor VIII deficiency, factor VIII inhibitors, von Willebrand disease, or disseminated intravascular coagulation (DIC). Levels may also be reduced in female carriers of Hemophilia A. Since factor VIII is an acute phase reactant, levels are elevated by stress, inflammation, surgery, exercise, pregnancy, or estrogen therapy.
Additional Test Information Normal Range 54-152%, effective 3/1/12
Sample Requirements Whole Blood:  3.2% Sodium Citrated (blue top)  OR
Frozen Plasma
Requested Volume Two 5 ml 3.2 sodium citrated (blue top) tubes as whole blood  OR
Frozen plasma in 4 X 1mL aliquots in plastic tubes 
Minimum Volume or Pediatric volume Frozen Plasma:  at least 0.5ml in 2 plastic tubes.  
Sample Information Whole blood is preferred for testing but if it is not possible to send whole blood tubes TO ARRIVE HERE WITHIN 2 HOURS of collection then send frozen plasma. To prepare plasma  centrifuge blue top tubes at 1500g for 15 minutes and remove the plasma and centrifuge a second time at 1500g for an additional 15 minutes.  Aliquot approximately 1 ml of plasma into 4 plastic tubes, and freeze.  
Shipping Information Whole Blood:  Send at ambient temperature (18-25C) and must be received within the lab in less than or equal to 3 hours after collection.
Frozen Plasma:  send on dry ice 

Send samples to:

Bloodworks Northwest
Attn: Hemostasis Laboratory
921 Terry Ave
Seattle, WA 98104

For additional information, please see Ordering Information
Requisition Form RFT- Hemostasis Reference Laboratory
Transaction Code 3210-13
CPT Codes 85240
Test Schedule Monday - Friday
Turn around Time (analytic time) 3 business days; available STAT (5 business days when ordered with VWD panel)
Report/ Results Fax number required to receive report