One 5 mL red to tube. Also acceptable: One 7.5 mL serum separator tube (SST).
Handling:
Allow to clot, centrifuge and immediately separate serum from cells into a plastic vial. Refrigerate. Freeze at -20° C if assay cannot be performed within 48 hours after collection.
Refrigerated specimen received in labortory more than 48 hours after collection; microbially contaminated, heat treated, grossly hemolyzed, or lipemic specimen.