Factor XI Inhibitor Evaluation, Plasma

Message

Sendout, Mayo test code: 11INE

Test Code

LAB1238011

Alias/See Also

Factor XI Inhibitor Screen, Plasma
11INE

CPT Codes
85390, 85270, 85335 (if appropriate), 85390 (if appropriate)

Includes

Testing begins with coagulation factor XI activity assay with dilutions to evaluate assay inhibition; if the factor XI activity assay is normal or increased, then a technical interpretation will be provided.

If the factor XI activity assay is decreased, then an inhibitor screen will be performed at an additional charge to look for specific factor XI inhibition and a professional interpretation will be provided. If specific inhibition is apparent, the titer of the inhibitor will be determined.

Preferred Specimen

3 plastic vials, each containing 1 mL platelet-poor plasma from a light blue (sodium citrate) tubes

Patient Preparation
1. Patient should not be receiving Coumadin (warfarin), heparin, direct thrombin inhibitors (argatroban, dabigatran), or direct factor Xa inhibitors (apixaban, rivaroxaban, and edoxaban).
2. Fasting preferred.

Minimum Volume

2 mL plasma in 2 plastic vials, 1 mL each

Instructions

1. Specimen must be collected prior to factor replacement therapy.
2. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.
3. Aliquot plasma (1-2 mL per aliquot) into 3 separate plastic vials, leaving 0.25 mL in the bottom of centrifuged vial.
4. Freeze plasma immediately (no longer than 4 hours after collection) at -20 degrees C or, ideally, < or =-40 degrees 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.

Transport Container

3 plastic vials

Transport Temperature

Frozen

Specimen Stability

Frozen: 14 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis: Reject
Gross lipemia: Reject
Gross icterus: Reject

Methodology
Optical Clot-Based

FDA Status
Approved

Setup Schedule

Monday through Friday

Report Available

1-3 days

Limitations

Occasionally, a potent lupus-like anticoagulant may cause false-positive testing for a specific factor inhibitor (eg, factor VIII or IX); see Ordering Guidance.

Reference Range

Included with report

Clinical Significance

Detection and quantitation of inhibitor to coagulation factor XI

This test is not useful for the detection of a lupus-like circulating anticoagulant inhibitor, a nonspecific circulating anticoagulant, or other inhibitors that are not specific for coagulation factors.

Performing Laboratory
Mayo Clinic Laboratories, Rochester, Minnesota

Additional Information
Factor XI Inhibitor Evaluation, Plasma

The CPT Codes provided in this document 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 payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.