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Test Code FXII Factor XII, Plasma

Additional Codes

Sunrise Clinical Manager (SCM) Orderable:   Factor XII Assay

AllScripts (AEHR) Orderable:  Factor XII Assay


Performing Laboratory

Northwell Health Laboratories


Clotting-Beckman Coulter-ACL® TOP/IL

Reference Values


Test Classification and CPT Coding


Day(s) and Time(s) Performed

Monday through Friday

Specimen Required

Container/Tube: Light blue-top (3.2% sodium citrate) tube

Specimen: 0.5 mL citrated plasma

Transport Temperature: Frozen


Collection Instructions:

  1. If the light blue top tube is the only tube to be drawn and will be collected using a butterfly set, a “discard” tube (either a plain[non-additive] or light blue) must be partially drawn just to completely fill the collection tubing with blood before collecting the light blue top for testing.  Failure to perform this step will result in an under-filled tube that the laboratory will reject.
  2. Allow blood to fill the tube completely to the line on the tube.  The ratio of blood to anticoagulant is critical in coagulation testing and at least a 90% fill is required.
  3. Immediately mix the specimen by gently inverting the tube 4-6 times to completely mix with the anticoagulant.  Failure to perform this can result in a clotted sample, which is unacceptable for testing.

If centrifugation of the specimen cannot be performed immediately after collection, whole blood can be kept in the blue top tube at room temperature (18-24° C) for up to 4 hours for the APTT and up to 24 hours for a PT/INR.  For additional coagulation assays, whole blood cannot be refrigerated or frozen.


If centrifugation is possible, and transport to the lab will not occur within 1 hour, spin down, remove the plasma to a clean plastic transport tube using a plastic transfer pipette, and spin the plasma again.  Remove the plasma with a clean plastic transfer pipette to a fresh transport container and freeze this citrated platelet-poor plasma immediately.  A double centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.   Each coagulation assay requested should have its own vial of citrated plasma, 1.0mL each.