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Test Code FXCH Coagulation Factor X Chromogenic Activity Assay, Plasma

Reporting Name

Factor X Chromogenic Activity Assay

Useful For

Monitoring warfarin anticoagulant therapy, especially in patients whose plasma contains lupus anticoagulants that interfere with baseline prothrombin time/international normalized ratio and in patients receiving the drug Argatroban who are being transitioned to warfarin

 

This assay should not be used for monitoring heparin, or oral direct factor Xa inhibitors such as rivaroxaban (Xarelto), apixaban (Eliquis), or edoxaban (Savaysa).

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Plasma Na Cit


Specimen Required


Patient Preparation: Fasting preferred

Collection Container/Tube: Light-blue top (citrate)

Submission Container/Tube: Polypropylene vial

Specimen Volume: 1 mL

Collection Instructions:

1. For complete instructions see Coagulation Guidelines for Specimen Handling and Processing

2. Spin down, remove plasma, and spin plasma again.

3. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally, at or below -40° C.

Additional Information:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

2. Each coagulation assay requested should have its own vial.

3. If priority specimen, mark request form, give reason, and request a call-back.


Barnes-Jewish Hospital Note:

For non hospital patient, call Barnes-Jewish Hospital Laboratory Customer Service at 314-362-1470 for STAT pick-up.

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen 14 days

Reference Values

≥18 years of age: 60%-140%

Chromogenic Factor X activity generally correlates with the one-stage factor X activity. In full term or premature neonates, infants, and children, the one-stage factor X activity* is lower than adult reference range and progressively rises to the adult reference range by adolescence. However, no similar data for the chromogenic factor X activity have been published.

 

*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing.

Day(s) Performed

Monday through Friday

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

85260

LOINC Code Information

Test ID Test Order Name Order LOINC Value
FXCH Factor X Chromogenic Activity Assay 33984-6

 

Result ID Test Result Name Result LOINC Value
FXCH Factor X Chromogenic Activity Assay 33984-6

Method Name

Chromogenic

Report Available

1 to 3 days
Barnes-Jewish Hospital Additional Information:

For BJH Laboratory Use Only
Laboratory Processing Instructions:
BJH Core lab will forward to the performing laboratory. Do not reject specimen if not received on ice.