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Test Code F11T Factor XI Inhibitor Titer

Specimen Type

Blood

Container

Two light blue top tubes, 3.2% sodium citrate

Preferred Volume

5.4 mL

Offsite Collection Instructions

  • Samples must be centrifuged at >1500 x g for 10 minutes at room temperature.
  • Carefully remove plasma from the cells using a plastic transfer pipette avoiding the buffy coat.
  • Aliquot the 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 or send the 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.

Availability

Monday – Friday. 8:00 am – 12:00 noon

Turnaround Time

Monday to Friday: 20 hours.

STAT Availability

Not Available

Test Usage

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

Test Methodology

Clotting

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

85335

Minimum Volume

5.4 mL

Reference Range

<0.6 Bethesda Units

Fee Code

30785335

Synonyms

Factor XI (11) Inhibitor Titer