FACTOR IX INHIBITOR EVALUATION
General Information
HLAB/HOL Code: FAC9I
UPHSM LIS Test #:
Schedule:
Testing Time: 2-5 Days
Testing Lab: LabCorp
UPHSM LIS Test #:
Schedule:
Testing Time: 2-5 Days
Testing Lab: LabCorp
Specimen Info
Only 1 specimen type required, unless otherwise specified
Volume: 4 mL in 2 vials
Temperature: Frozen
Tube Type: Platelet Poor Plasma (sodium citrate)
Collection Info:
Volume: 4 mL (2 mL in each of two tubes)
Container: Blue-top (sodium citrate) tubes
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 non-citrate 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 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 re-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 transport tube. 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.
Temperature: Frozen
Tube Type: Platelet Poor Plasma (sodium citrate)
Collection Info:
Volume: 4 mL (2 mL in each of two tubes)
Container: Blue-top (sodium citrate) tubes
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 non-citrate 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 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 re-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 transport tube. 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.
Methods
The factor IX inhibitor (Bethesda titer) assay is performed using an activated partial thromboplastin time (aPTT)-based system.6 Serial dilutions are made of patient plasma with veronal buffered saline, then mixed with normal plasma containing close to 100% factor IX activity and are then incubated for two hours. An aPTT-based factor IX assay using factor IX-depleted plasma substrate is then performed on these incubated mixtures. Results are compared to those of incubated normal plasma. One Bethesda unit is defined as the amount of factor IX inhibitor that neutralized 0.5 IU of factor IX in this system. The number of serial dilutions tested is based on the anticipated level of the inhibitor.
Clinical Utilities
Confirmation and characterization of factor IX inhibitor
CPT Codes
85250; 85335
* The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding
is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.
