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Test ID 2INHE Factor II Inhibitor Evaluation, Plasma

Ordering Guidance

This test is for factor II inhibitors only. If the presence or type of inhibitor is unknown, order APROL / Prolonged Clot Time Profile, Plasma first, except for when screening studies are needed for patients with known hemophilia A or B.

Shipping Instructions

Send all vials in the same shipping container.

Necessary Information

If priority specimen, mark request form, give reason, and request a call-back.

Specimen Required

Patient Preparation:

1. Patient must not be receiving Coumadin (warfarin) or heparin therapy

2. Fasting preferred

Specimen Type: Platelet-poor plasma

Collection Container/Tube: Light-blue top (3.2% sodium citrate)

Submission Container/Tube: Plastic vials

Specimen Volume: 3 mL in 3 plastic vials each containing 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 in Special Instructions.

3. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.

4. Aliquot 1-2 mL of plasma into 3 separate plastic vials 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, ≤-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.

Useful For

Detection and quantitation of inhibitor to factor II


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.

Profile Information

Test ID Reporting Name Available Separately Always Performed
2INHT FII Inhib Profile Tech Interp No Yes
F_2 Coag Factor II Assay, P Yes Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
2AINH FII Inhib Profile Prof Interp No No
F2_IS Factor II Inhib Scrn No No
GBETH General Factor Bethesda Units, P No No

Testing Algorithm

Testing begins with coagulation factor II activity assay with dilutions to evaluate assay inhibition; if the factor II activity assay is normal or increased, a technical interpretation will be provided. If the factor II activity assay is decreased, an inhibitor screen will be performed at an additional charge to look for specific factor II inhibition and a professional interpretation will be provided. If specific inhibition is apparent, the titer of the inhibitor will be determined.

Method Name

Optical Clot-Based

Reporting Name

Factor II Inhib Profile, P

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

2 mL in 2 plastic vials, 1 mL each

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen 14 days

Reference Values


Adults: 75-145%

Normal, full-term newborn infants or healthy premature infants may have decreased levels (≥25%) which may remain below adult levels for ≥180 days postnatal.*

*See Pediatric Hemostasis References in Coagulation Guidelines for Specimen Handling and Processing in Special Instructions. 

Day(s) Performed

Monday through Friday

Report Available

1 to 3 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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.

CPT Code Information

85390 - Factor II Tech Interp

85210 - Factor II

85335 - Factor inhibitor (if appropriate)

85335 - Bethesda units (if appropriate)

85390 - Factor II Professional Interp (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
2INHE Factor II Inhib Profile, P 96455-1


Result ID Test Result Name Result LOINC Value
F_2 Coag Factor II Assay, P 3289-6
2INHT FII Inhib Profile Tech Interp 69049-5


If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.