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Factor 8 Activity, Chromogenic

Item Value
Approval req'd? No
Available Stat? No
Test code F8CH
Performed by Quest
Sendout? Yes
Method Chromogenic assay
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 (415-353-1747) 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
Amount to Collect 2.7 mL blood
Sample type Citrated plasma
Preferred volume 1 mL plasma
Min. Volume 0.5 mL plasma
UCSF Rejection Criteria Samples collected in outdated blue top vacutainer. Over-filled or under-filled tubes may be rejected. Hemolyzed specimens are not acceptable.
Processing notes Deliver sample to Hematology Lab ASAP for processing.

Separate platelet poor plasma. Freeze 1 mL of plasma in a plastic tube at
-20C. Order Quest test# 16049X.

Ship Monday-Friday frozen and on dry ice to Send-outs at China Basin.
Units % activity
Normal range 65-179% Avtivity
Synonyms F8 Chromogenic; Factor VIII Activity, Chromogenic
Stability Frozen plasma is stable for 2 weeks at -20C or 6 months at -70C.
Turn around times Run Thursday, turnaround time 7-10 days
Additional information The chromogenic Factor VIII activity assay may clarify diagnosis and classification of severity of hemophilia A when the regular (one-stage clot based) Factor VIII activity assay provides results at variance with clinical impression. A Factor VIII activity/Chromogenic Factor VIII activity ratio of less than or equal to 0.5 or greater than or equal to 2.0 is considered to be atypical. In patients with atypical ratios, the chromogenic Factor VIII assay may correlate with clinically observed bleeding.
CPT coding 85240-90
LOINC code 49865-9
Last Updated 9/18/2012 2:27:13 PM
Entry Number 1294
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