Factor XII Activity

Profile or Test Panel
Method Clottable
Test Information A one-stage intrinsic system clotting assay is used to measure circulating factor XII levels. Clotting times of dilutions of patient plasma are compared to dilutions of a plasma pool from normal donors, when added to deficient plasma. A deficiency of FXII is not associated with bleeding.
Additional Test Information Normal ranges are included on testing report and can be made available upon request.
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 (18-25°C) and must be received within the lab in less than or equal to 2 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 3210-17
CPT Codes 85280
Test Schedule Monday – Friday
Turn around Time (analytic time) 3 Business Days
Report/Results Fax number required to receive report

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