Factor 11 activity-13369

Test info

  
Factor 11 activity
  
13369
  
LAB13369
  
F11
  
Antihemophilic factor C
Factor XI activity
Plasma thromboplastin antecedent (PTA)
  

To evaluate isolated APTT prolongation and to document specific factor XI deficiency

Specimen

  
  • Ideally, the patient should not be on anticoagulant therapy
  • Avoid warfarin (Coumadin®) therapy for two weeks prior to the test and heparin, direct Xa, and thrombin inhibitor therapies for about three days prior to testing
  
Sodium citrate (Na cit) plasma
  

Lt blue Sodium citrate (NaCit)

  
1.0 mL
  
  • Do not draw from an arm with a heparin lock or heparinized catheter
  • Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate
  • Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio
  • The sample should be mixed immediately by gentle inversion, at least six times, to ensure adequate mixing of the anticoagulant with the blood
  • A discard tube is not required prior to collection of coagulation samples unless the sample is collected using a winged (butterfly) collection system
    • With a winged blood collection set a discard tube should be drawn first to account for the dead space of the tubing and prevent under-filling of the evacuated tube
  • When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes.
    • Any tube containing an alternative anticoagulant should be collected after the blue-top tube
    • Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes
  • If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted
  
  1. Spin within two (2) hours of sample collection
  2. Transfer plasma to a Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp), labelled as Na cit plasma
  3. Freeze
  

Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp)

  

Frozen - 28 days

Freeze/thaw cycles - stable x3

  
  • Severe hemolysis
  • Improper labeling
  • Clotted specimen
  • Specimen diluted with I.V. fluids
  • Samples thawed in transit
  • Improper sample type
  • Sample out of stability

Performance

  
LabCorp Burlington (086314): R-LC
  
Daily
  
2 - 3 days
  

Factor XI activity is determined utilizing an aPTT-based one-stage clotting time assay. Factor XI-depleted plasma is used as the substrate and the clotting time with the patient plasma is compared to the clotting time of normal pooled plasma.

Clinical and Interpretive info

  

60 - 150%

Billing

  
85270
  
Result 3226-8

Tracking

  
03/29/2019
  
05/31/2024
  
12/29/2023