Specimen Requirements

Preferred:  Plasma

Draw blood in a light green-top (PST - lithium heparin gel) tube(s). (Hemolyzed specimen is not acceptable.) Spin down, separate plasma from cells within 2 hours of collection, and send 1 mL of lithium heparin plasma refrigerated.

Note:  Label specimen as “plasma”. 

Acceptable:  Serum

Draw blood in a plain, red-top tube(s) or SST- serum gel tube(s). (Hemolyzed specimen is not acceptable.) Centrifuge, separate serum from cells within 2 hours of collection, and send 1 mL of serum refrigerated.

Note:  Label specimen as “serum”

Precaution:  Do not order on patients who have recently received methotrexate or other folic acid antagonist.