Test Directory

This test is used for the measurement of prekallikrein factor activity.

Specimen Type: Citrated Platelet-Poor Plasma

Collection Container: Light Blue Top (Sodium Citrate)

Desired Specimen Volume: 1 mL

1. Collect a light blue top (sodium citrate) tube via venipuncture
2. Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.
3. The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood.
4. 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.
5. 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.

 Platelet-Poor Plasma Processing Instructions

1. Perform platelet-poor plasma procedure.
2. Transfer 1 mL of platelet poor plasma to a LabCorp pp transpak frozen purple tube.
3. Freeze immediately.
4. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.

Do not draw from an arm with a heparin lock or heparinized catheter.

Transport to the laboratory frozen. 

 See patient report.

Plasmas deficient in FXII may give falsely low results. Lupus anticoagulants and other non-specific factor inhibitors may also interfere with this assay. Heparin, direct Xa or thrombin inhibitor therapy may have an effect on factor assays.

•  Fletcher Factor Assay