Here is a note from participant “dsadowski” at Southampton Hospital:
What are some guidelines for determining whether a specimen is citrated plasma vs. serum or another anti-coagulated plasma? My fibrinogen testing is PT-derived, so relying on a low fibrinogen value would not be helpful for determining serum vs. citrated plasma.
Thank you for your question. Specimen integrity is a particular problem for coagulation reference laboratories that receive no specimens in their original collection tubes, rather they receive only frozen plasma specimens. Lab scientists easily discern serum specimens from the PT and PTT, or the fibrinogen concentration, as suggested. However, there is little way to learn if the specimen was partially clotted or if it was erroneously collected in the wrong additive tube, for instance EDTA. I found only one EDTA study; Green D, McMahon B, Foiles N, Tian L. Measurement of hemostatic factors in EDTA plasma. Am J Clin Pathol 2008;130:811-5. This group at Northwestern University Hematology/Oncology Department in Chicago found no statistical difference between levels of factor VII antigen, factor VIII antigen, and VWF antigen, but slight differences for factor VIII coagulant activity. From this study it may be difficult to detect an EDTA specimen.
I’d like to hear from some of our friends in reference laboratories to see if they have developed any internal guidelines they would like to share.