Factor VIII Activity with Reflex to Bethesda Quantitative, Factor VIII
Also known as: F8 BETHR
Use
This test is primarily ordered to diagnose factor VIII deficiency, detect factor VIII inhibitors, and monitor factor VIII replacement therapy. Factor VIII is a critical blood coagulation protein, and deficiencies or inhibitors can lead to bleeding disorders such as hemophilia A. This test helps in identifying the presence of inhibitors that neutralize factor VIII, which is crucial for the management and treatment planning in patients receiving factor VIII concentrates.
Special Instructions
Separate specimens must be submitted when multiple tests are ordered. Collection involves using a Lt. blue (sodium citrate) tube and transferring two 3 mL aliquots of platelet-poor plasma to ARUP standard transport tubes. The specimen must be critically frozen for transport.
Limitations
This test has some limitations, particularly if factor VIII activity is greater than 20 percent, which can prevent conducting the Bethesda quantitative factor VIII inhibitor study. False positives can also occur in patients with heparin, direct oral anticoagulants, or lupus anticoagulants. It is important to correlate the test results with clinical information and possibly perform additional laboratory testing for accurate diagnosis.
New York Approved
Methodology
Other
Biomarkers
LOINC Codes
- 3204-5
- 3209-4
- 3204-5
- 3209-4
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
3 mL
Minimum Volume
2 mL each
Container
ARUP standard transport tubes
Collection Instructions
Collect using a Lt. blue (sodium citrate) tube, then transfer two 3 mL aliquots of platelet-poor plasma.
Storage Instructions
CRITICAL FROZEN.
Causes for Rejection
Serum, EDTA plasma, clotted or hemolyzed specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 4 hours |
| Refrigerated | Unacceptable |
| Frozen | 3 months |