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Test Code F8IT Factor VIII Inhibitor Titer

Specimen Type



Two light blue top tubes, 3.2% sodium citrate

Preferred Volume

5.4 mL

Offsite Collection Instructions

Whole blood sample must arrive in the laboratory within three hours of specimen collection.


If transport time exceeds three hours, follow centrifugation instructions:

  • Samples must be centrifuged at >1500 x g for 10 minutes at room temperature.
  • Carefully remove the plasma from the cells using a plastic transfer pipette avoiding the buffy coat.
  • Aliquot removed plasma into 2 plastic tubes containing a minimum of 1000 uL of specimen in each tube.
  • The plasma samples must then be frozen at -20ºC.
  • Once solidly frozen, they must be shipped on dry ice. Samples that have thawed in transit will be rejected.

Note: For clients who do not have access to dry ice DO NOT freeze the specimen. Follow the centrifugation instructions and send fresh plasma or send whole blood sample. It now becomes vital that the specimen arrives in the lab within three hours of collection.

UCMC Collection Instructions

Specimens can be collected 24/7. Samples received in the lab after 12:00 pm (Monday-Thursday) will be run the next morning. Samples received after 12:00 pm on Friday will be run on Monday morning.


Monday – Friday, 8:00 a.m. to 12:00 noon

Turnaround Time

Monday to Friday: 20 hours.

STAT Availability

Not Available

Test Usage

Note: Bethesda assay for Factor VIII inhibitor titers generally performed only in the setting of significantly decreased levels of Factor VIII.

Test Methodology


Additional Information

All 3.2% sodium citrate light blue top tubes require a ratio of 9 parts blood to 1 part anticoagulant (example: a 3.0 mL tube requires 2.7 mL blood added to 0.3 mL of anticoagulant).

CPT Code


Test Includes

Factor VIII inhibitor titer

Reference Range

<0.6 Bethesda Units

Minimum Volume

5.4 mL

Fee Code



Factor VIII (8) Inhibitor Titer