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Test ID F9INH Factor IX Inhibitor Evaluation

Useful For

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

Special Instructions

Method Name

F_9: Activated Partial Thromboplastin Time-Based Clotting Assay

F9_IS, IBETH: Clot-Based Assay

Reporting Name

Factor IX Inhib Profile

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

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

Performing Laboratory

Mayo Medical Laboratories in Rochester

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

Test Classification

See Individual Test IDs

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.