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HelpTest ID BLOD0116 Coagulation Factor XI Activity Assay, Plasma
Useful For
Diagnosing deficiency of coagulation factor XI
Investigating prolonged activated partial thromboplastin time
Specimen Type
Plasma Na CitOrdering Guidance
Coagulation testing is highly complex, often requiring the performance of multiple assays and correlation with clinical information. For that reason, consider ordering a Coagulation Consultation.
Necessary Information
If priority specimen, mark request form, give reason, and request a call-back.
Specimen Required
Specimen Type: Platelet-poor plasma
Patient Preparation: Patient must not be receiving Coumadin (warfarin) or heparin therapy.
Collection Container/Tube: Light-blue top (3.2% sodium citrate)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Specimen must be collected prior to factor replacement therapy.
2. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing.
3. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.
4. Aliquot plasma into a plastic vial, leaving 0.25 mL in the bottom of centrifuged vial.
5. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or ideally, at or below -40° C.
Additional Information:
1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.
2. Each coagulation assay requested should have its own vial.
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma Na Cit | Frozen | 14 days |
Day(s) Performed
Monday through Saturday
Report Available
1 to 3 daysMethod Name
Optical Clot-Based
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
85270
Reporting Name
Coag Factor XI Assay, PReference Values
Adults: 55-150%
Normal, full-term newborn infants or healthy premature infants may have decreased levels (≥10%), which may not reach adult levels for 180 or more days postnatal.*
*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing.
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.Forms
If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.
Special Instructions
SANFORD LABORATORY INTERFACE BUILD INFORMATION
| Result Code | Result Code Description |
|---|---|
| 13053 | Coag Factor XI Assay, P |