FVIII Chromogenic

Panels that include this biomarker

• Factor VIII Chromogenic Bethesda Profile, for Patients on Emicizumab 504722

  3 analytes · Plasma · Fasting not stated · Turnaround 5 - 10 days

  Method and collection

  Method

  The Nijmegen modification of the classic Bethesda inhibitor titration assay is used in a chromogenic factor VIII activity setting. Patient sample is heat-inactivated and clarified, then a serial dilution series is prepared in buffered normal plasma containing bovine serum albumin. A chromogenic factor activity is measured to determine residual activity and the inhibitor concentration is determined using an equation that relates the log % residual activity to inhibitor titer.

  Preparation

  The patient should not be anticoagulated. Do not draw from an arm with a heparin lock or heparinized catheter.

  Collection

  Citrated plasma samples should be collected by 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 nonadditive (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. 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 No. 49482). Freeze immediately and maintain frozen until tested. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

  Labcorp catalog page

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