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Factor Inhibitor Titer

Item Value
Approval req'd? The factor inhibitor titer may require approval by the Lab Medicine resident. Approval will depend on: (1) patient's clinical history, (2) patient's response to factor therapy, and (3) laboratory results such as the inhibitor screen and factor activity assays.
Available Stat? No
Test code FIT
Test group Factor Inhibitor Titer
Performed by Parnassus Hematology
Collection Instructions 1. Check the expiration date on the label of the blue top vacutainer before drawing the patient.

2. For blood collection in a sodium citrate blue top, the tube must be filled to above the Minimum Fill Indicator on the tube. It is crucial to wait and allow the tube to stop filling before removing it from the needle.

3. With use of a butterfly needle, draw about 1 cc using a separate blue top to remove air from tubing, discard the first tube and then draw a second blue top tube filled to the full extent of the vacuum.

4. Tubes should not be filled past the Maximum Fill dashed line by either using a syringe or removing the tube cap.

Deliver immediately to the laboratory.

For patients with Hct's ≥ 55% please contact Hematology (Parnassus: 3-1747, Mission Bay 6-1094) to obtain blue top tubes with adjusted citrate volumes in order to maintain the proper citrate to plasma ratio for coagulation studies.
Container type Blue top filled to full extent of vacuum x2
Amount to Collect 5.4 mL blood
Sample type Citrated plasma
Preferred volume 3 mL plasma
Min. Volume 2 mL plasma
UCSF Rejection Criteria Samples collected in outdated blue top vacutainer. Over-filled or under-filled tubes may be rejected
Processing notes Deliver specimen to Hematology section for processing ASAP
Units Bethesda units (BU)
Normal range <0.1 BU
Synonyms F8 inhibitor titer; Factor 8 inhibitor titer; FVIII inhibitor titer; Factor VIII inhibitor titer F9 inhibitor titer; Factor 9 inhibitor titer; FIX inhibitor titer
Stability The plasma for a Factor Inhibitor Titer must be frozen within four hours of specimen collection.

The frozen plasma is stable for 2 weeks at -20C or 6 months at -70C.
Turn around times 2 weeks
Additional information The inhibitor titer assay, which was originally intended for the measurement of inhibitors occurring in hemophiliacs, can be used with modifications for acquired factor inhibitors from non-hemophiliacs.

Heparin contamination or contamination with other anticoagulants may invalidate results of a factor inhibitor titer.

If unusual findings are noted a pathologist review and interpretation may be performed and separately billed for
CPT coding 85335 x 6
LOINC code 13591-3
LDT or Mod FDA? Yes
Last Updated 6/20/2016 1:03:52 PM
Entry Number 357
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