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Test Mnemonic F9INH Factor IX Inhibitor Evaluation

Reporting Name

Factor IX Inhib Profile

Useful For

Detection and titering of coagulation inhibitor to the specific factor requested, primarily factor IX in patients with hemophilia B

Profile Information

Test ID Reporting Name Available Separately Always Performed
F_9 Coag Factor IX Assay, P Yes Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
IBETH Bethesda Units No No
F9_IS Factor IX Inhib Scrn No No
CCCR Special Coagulation Interpretation 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 decreased, an inhibitor will be performed to look for specific factor IX inhibition. If specific inhibition is apparent, it will be titered.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Plasma Na Cit


Specimen Required


See Coagulation Studies in Special Instructions.

 

Specimen Type: Platelet-poor plasma

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

Submission Container/Tube: Plastic vials

Specimen Volume: 3 mL in 3 plastic vials each containing 1 mL

Collection Instructions:

1. Specimen must be drawn prior to factor replacement therapy.

2. Spin down, remove plasma, and spin plasma again.

3. Freeze specimens immediately at ≤-40 degrees C, if possible.

4. Send specimens in the same shipping container.

Additional Information:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

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

3. Each coagulation assay requested should have its own vial.


Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Na Cit Frozen 14 days

Special Instructions

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 in Coagulation Studies in Special Instructions.

 

FACTOR IX INHIBITOR SCREEN

Negative

 

BETHESDA TITER

0 Units

Day(s) and Time(s) Performed

Monday through Friday; Varies

CPT Code Information

85250-Factor IX activity assay

85335-Bethesda titer (if appropriate)

85335-Factor IX inhibitor screen (if appropriate)

85390-26-Special coagulation interpretation (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
F9INH Factor IX Inhib Profile 3187-2

 

Result ID Test Result Name Result LOINC Value
F_9 Coag Factor IX Assay, P 3187-2

Method Name

F_9: Activated Partial Thromboplastin Time-Based Clotting Assay

F9_IS, IBETH: Clot-Based Assay

Test Classification

See Individual Test IDs