Factor VIII Chromogenic Bethesda Profile, for Patients on Emicizumab
Use
This assay is used to quantitate the titer of specific factor VIII antibodies in patients receiving emicizumab / Hemlibra®. Use of a standard, clot-based factor VIII test system will not accurately determine inhibitor titer due to interference from the therapeutic.
Special Instructions
Testing is performed at Esoterix Coagulation Laboratory (UY No. 301676). This test is not intended for use with any other therapeutic besides emicizumab.
Limitations
Hemolysis, lipemia, and icterus may interfere with this assay, leading to inaccurate results. Direct Xa inhibitors can cause erroneous low factor activity and false positive factor inhibitor results. Residual factor VIII activity, although limited by heat-inactivation of the sample, can falsely lower the Bethesda titer. Autoimmune inhibitors demonstrating second order kinetics may not be accurately measured by this system.
Methodology
Other
Biomarkers
LOINC Codes
- 3209-4
- 49865-9
- 93450-5
- 3209-4
- 49865-9
- 93450-5
Result Turnaround Time
5-10 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
2 mL
Minimum Volume
1 mL
Container
Blue-top (sodium citrate) tube
Collection Instructions
Citrated plasma samples should be collected by double centrifugation. Blood must be collected in a blue-top tube with 3.2% buffered sodium citrate. The tube must be filled completely to ensure a proper blood to anticoagulant ratio, and mixed immediately by gentle inversion at least six times.
Patient Preparation
The patient should not be anticoagulated. Do not draw from an arm with a heparin lock or heparinized catheter.
Storage Instructions
Freeze.
Causes for Rejection
Patients on therapy other than emicizumab. Any sample not being citrated plasma (3.2% sodium citrate). Samples showing signs of activation, or received thawed.
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 12 months |