Coagulation Factor XI Activity Assay, Plasma
Use
The Coagulation Factor XI Activity Assay is useful for diagnosing deficiency of coagulation factor XI, which may cause prolonged activated partial thromboplastin time. Factor XI is synthesized in the liver and is a component of the intrinsic coagulation pathway. Activation of factor XI leads to the activation of factor IX to IXa. Deficiency of factor XI is associated with mild bleeding diathesis and is more prevalent among individuals of Ashkenazi Jewish descent. Evaluating factor XI levels is crucial in the context of both congenital and acquired deficiencies, which may have implications for bleeding risk and management.
Special Instructions
For patients not receiving electronic orders, a completed Coagulation Test Request form (T753) must accompany the specimen. Ordering guidance suggests that coagulation testing is complex; consider ordering a Coagulation Consultation for expert interpretation of results. Double-centrifuging the specimen is critical, as platelet contamination can lead to inaccurate results. Each coagulation assay requested should have its own vial.
Limitations
Decreased plasma levels of factor XI do not correlate well with bleeding risk, which presents challenges in clinical interpretation. Improper specimen collection and handling can result in diagnostic inaccuracies, as can inappropriate test selection or interfering substances. Common issues include sample contamination with agents like heparin or warfarin, which patients must avoid prior to sample collection.
New York Approved
Methodology
Other (Optical Clot-Based)
Biomarkers
LOINC Codes
- 3226-8
- 3226-8
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
0.5 mL
Container
Light-blue top (3.2% sodium citrate)
Collection Instructions
Specimen must be collected prior to factor replacement therapy. Follow Coagulation Guidelines for Specimen Handling and Processing: 1. Centrifuge and transfer all plasma into a plastic vial, centrifuge plasma again. 2. Aliquot plasma into a plastic vial, leaving 0.25 mL in the bottom. 3. Freeze immediately at -20 to -40 degrees C.
Patient Preparation
Patient must not be receiving Coumadin (warfarin) or heparin therapy.
Causes for Rejection
Gross hemolysis, gross lipemia, and gross icterus.
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |