Factor X, Chromogenic

Single-analyte tests

• Factor X, Chromogenic 117904

  Plasma · Fasting not stated · Turnaround 2 - 3 days

  Method and collection

  Method

  Factor X is activated by Russell viper venom which, in turn, hydrolyzes a chromogenic substrate to produce color.

  Collection

  Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.14 Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.15,16 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.17,18 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. 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 recentifuge for 10 minutes. Use a second plastic pipette to remove 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 No. 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when, please submit separate frozen specimens for each test requested . Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

  Reference notes

  • Nonanticoagulated subjects: 82% to 151% • Anticoagulant therapeutic range: 20% to 40% corresponds to an INR range of 2.0−3.0

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