Test Code 9INHE Factor IX Inhibitor Evaluation, Plasma
Ordering Guidance
This test is for factor IX inhibitors only. If the patient is known to have hemophilia B, this is the correct test to order. If the presence or type of inhibitor is unknown, first order APROL / Prolonged Clot Time Profile, Plasma. When screening studies are needed for patients with known hemophilia A, order 8INHE / Factor VIII Inhibitor Evaluation, Plasma.
Shipping Instructions
Send all vials in the same shipping container.
Necessary Information
Specimen Required
Specimen Type: Platelet-poor plasma
Patient Preparation:
1. Patient must not be receiving Coumadin (warfarin) or heparin therapy
2. Fasting preferred
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.
3. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.
4. Aliquot plasma (1-2 mL per aliquot) 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, at -40° C or below.
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 titering of coagulation inhibitor to the specific factor requested, primarily factor IX in patients with hemophilia B
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 |
---|---|---|---|
9INHT | FIX Inhib Profile Tech Interp | No | Yes |
F_9 | Coag Factor IX Assay, P | Yes | Yes |
Reflex Tests
Test ID | Reporting Name | Available Separately | Always Performed |
---|---|---|---|
9AINH | FIX Inhib Profile Prof Interp | No | No |
9BETH | FIX Bethesda Units, P | No | No |
F9_IS | Factor IX Inhib Scrn | No | No |
Testing Algorithm
Testing begins with coagulation factor IX activity assay with dilutions to evaluate assay inhibition; if the factor IX activity assay is normal or increased, then a technical interpretation will be provided.
If the factor IX activity assay is decreased, then an inhibitor screen will be performed at an additional charge to look for specific factor IX inhibition and a professional interpretation will be provided. If specific inhibition is apparent, the titer of the inhibitor will be determined.
Special Instructions
Method Name
F_9, 9BETH, F9_IS: Optical Clot-Based
9INHT: Technical Interpretation
9AINH: Medical Interpretation
Reporting Name
Factor IX Inhib Profile, PSpecimen Type
Plasma Na CitSpecimen Minimum Volume
2 Plastic vials, each containing 1 mL
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Plasma Na Cit | Frozen | 14 days |
Reference Values
FACTOR IX ACTIVITY ASSAY
Adults: 65-140%
Normal, full-term newborn infants or healthy premature infants may have decreased levels (≥20%) that may not reach adult levels for 180 days or more postnatal.*
*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing.
FACTOR IX INHIBITOR SCREEN:
Negative
GENERAL FACTOR BETHESDA UNITS:
≤0.4 Bethesda Units
Interpretation
Normally, there is no inhibitor (ie, negative result).
If the screening assays indicate the presence of an inhibitor, it will be quantitated and reported in Bethesda (or equivalent) units.
Clinical Reference
1. Hoffman R, Benz Jr EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Elsevier; 2018
2. Chitlur M, Warrier I, Rajpurkar M, et al. Inhibitors in factor IX deficiency a report of the ISTH-SSC international FIX inhibitor registry (1997-2006). Haemophilia. 2009;15(5):1027-1031. doi:10.1111/j.1365-2516.2009.02039.x
Day(s) Performed
Monday through Friday
Report Available
1 to 3 daysPerforming Laboratory
Mayo Clinic Laboratories in RochesterTest 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
85250
85335 (if appropriate)
85335 (if appropriate)
85390 (if appropriate)
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
9INHE | Factor IX Inhib Profile, P | 96459-3 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
9INHT | FIX Inhib Profile Tech Interp | 69049-5 |
F_9 | Coag Factor IX Assay, P | 3187-2 |
Forms
If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.