Test directory: Prekallikrein Assay

Ordering Code8329
Test NamePrekallikrein Assay
AliasFletcher factor
Preferred SpecimenPlasma
Preferred ContainerCitrate - Blue Top
Optimum Volume2 mL
DOUBLE CENTRIFUGATION. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.[1] Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.[2,3] 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, except when using a winged blood collection device (ie, "butterfly"), in which case a discard tube should be used. [4,5]
When noncitrate tubes are collected for other tests, collect sterile and non-additive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternate 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. Centrifuge for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette, being careful not to disturb the cells. Deliver to a plastic transport tube, cap, and recentrifuge for 10 minutes. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube. Transfer the plasma into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested

Please print and use the Volume Guide for
Coagulation Testing to ensure proper draw volume.
Handling InstructionsTesting is performed at Esoterix Coagulation
Laboratory: UY#300121
Transport RequirementsOahu: Frozen
Airline: Frozen
Specimen StabilityAmbient: 4 Hours
Avail. StatNO
Analytic Time4 - 8 days
MethodologyFactor prekallikrein activity is determined utilizing an aPTT-based one-stage clotting time assay. Factor prekallikrein-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.
Reference Lab Colorado Coagulation Consult.

Reference range(s)

ComponentAgeMale NormMale Critical LowMale Critical HighFemale NormFemale Critical HighFemale Critical LowUnitsAdd'l info
Prekallikrein AssayALLSee report.