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Test Code F8INH Factor VIII Inhibitor Evaluation

Reporting Name

Factor 8 Inhib Prof

Useful For

Detecting the presence and titer of a specific factor inhibitor directed against coagulation factor VIII  

 

This test is not useful for detecting the presence of inhibitors directed against other clotting factors and will not detect the presence of lupus anticoagulants.

Profile Information

Test ID Reporting Name Available Separately Always Performed
F8A Coag Factor VIII Activity Assay, P Yes Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
IBETH Bethesda Units No No
F8IS Coag Factor VIII Assay Inhib Scrn,P No No
CCCR Special Coagulation Interpretation No No

Testing Algorithm

Testing begins with coagulation factor VIII activity assay with dilutions to evaluate assay inhibition; if the factor VIII activity assay is decreased, an inhibitor screen will be performed to look for specific factor VIII inhibition. If specific inhibition is apparent, the titer of the inhibitor will be determined.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Plasma Na Cit


Advisory Information


This test is for factor VIII inhibitors only. If the presence or type of inhibitor is unknown, PROCT / Prolonged Clot Time Profile or LUPPR / Lupus Anticoagulant Profile should be ordered first.



Shipping Instructions


Send all vials in the same shipping container.



Specimen Required


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

 

Patient Preparation: Fasting preferred

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. Centrifuge, remove plasma, and centrifuge plasma again.

3. 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. If a 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 VIII ACTIVITY ASSAY

Adults: 55-200%

Normal, full-term newborn infants or healthy premature infants usually have normal or elevated factor VIII.*

*See Pediatric Hemostasis References in Coagulation Studies in Special Instructions.

 

FACTOR VIII INHIBITOR SCREEN

Negative

 

BETHESDA TITER

0 Units

Day(s) and Time(s) Performed

Monday through Friday; Varies

CPT Code Information

85240-Factor VIII activity assay

85335-Bethesda titer (if appropriate)

85335-Factor VIII inhibitor screen (if appropriate)

85390-26-Special coagulation interpretation (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
F8INH Factor 8 Inhib Prof 3209-4

 

Result ID Test Result Name Result LOINC Value
F8A Coag Factor VIII Activity Assay, P 3209-4

Method Name

Optical Clot-Based

Test Classification

See Individual Test IDs