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Test Code F9INH Factor IX Inhibitor Evaluation, Plasma

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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 detecting a nonspecific circulating anticoagulant or the presence of inhibitors directed against other clotting factors.

 

This test is not useful for the detection of lupus anticoagulants.

Method Name

Optical Clot-Based


Advisory Information


This test is for factor IX inhibitors only. If the presence or type of inhibitor is unknown, either APROL / Prolonged Clot Time Profile, Plasma or ALUPP / Lupus Anticoagulant Profile, Plasma should be ordered first.



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


See Coagulation Studies in Special Instructions: Guidelines for Specimen Handling and Processing.

 

Patient Preparation: 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. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.

3. Aliquot plasma into 3 separate plastic vials (1 mL in each) leaving 0.25 mL in the bottom of centrifuged vial.

4. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C, or ideally ≤-40 degrees 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.


Reporting Name

Factor IX Inhib Profile

Specimen Type

Plasma Na Cit

Specimen 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

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

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

Test Classification

See Individual Test IDs

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

Special Instructions

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

Profile Information

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

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.