Factor XI Activity

Profile or Test Panel
Method Clottable
Test Information A one-stage intrinsic system clotting assay is used to measure circulating factor XI 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 in hereditary factor XI deficiency, in the presence of a factor XI inhibitor, liver disease, or disseminated intravascular coagulation (DIC).
Additional Test Information Normal Range: 77-136%, effective 11/1/11
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 3 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 3210-16
CPT Codes 85270
Test Schedule Monday - Friday
Turn around Time (analytic time) 1 Business Day
Report/ Results Fax number required to receive report