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HelpTest ID 9INHE Factor IX Inhibitor Evaluation, Plasma
Ordering Guidance
This test is for factor IX inhibitors only. If the presence or type of inhibitor is unknown, order APROL / Prolonged Clot Time Profile, Plasma, 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: 3 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 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, ≤-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 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
Optical Clot-Based
Reporting Name
Factor IX Inhib Profile, PSpecimen Type
Plasma Na CitSpecimen Minimum Volume
2 mL plasma in 2 plastic vials, 1 mL each
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%), which may not reach adult levels for ≥180 days postnatal.*
*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing in Special Instructions.
Day(s) Performed
Monday through Friday
Report Available
1 to 3 daysPerforming 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 IX Tech Interp
85250-Factor IX activity assay
85335-Bethesda titer (if appropriate)
85335-Factor IX inhibitor screen (if appropriate)
85390-Factor IX Professional Interp (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.