From our frequent contributor, Kim Kinney at Indiana University Health Pathology Laboratory: Merry Christmas all! George, this may be an old topic, but I am getting some push back from our off-site coordinators. Coagulation samples sent on ice: I have always thought that the current literature stated that iced coag tubes could activate factor VII and potentially shorten the prothrombin time (PT). Is there current literature out there surrounding this topic? Any information would be helpful!
Hi, Kim, Merry Christmas to you, and happy holidays to all the folks at IU Health and all our participants. In medicine, it seems like old habits die hard, even when it they are contraindicated. I like to think that this is because we are all trying our hardest to get it right. The Clinical and Laboratory Standards Institute provides the most authoritative statement in their H21-A5 Guideline, Collection, Transport, and Processing of Blood Specimens for Testing Plasma-Based Coagulation Assays and Molecular Hemostasis Assays; Approved Guideline–Fifth Edition 2007. They require transport at ambient temperature and write, “Transportation of whole blood specimens on ice is not recommended for most plasma-based coagulation assays because of possible cold activation of factor VII, loss of von Willebrand factor, and platelet disruption.” Their reference is van Geest-Daalderop JH, Mulder AB, Boonman-de Winter LJ, et al . Preanalytical variables and off-site blood collection: influences on the results of the prothrombin time/international normalized ratio test and implications for monitoring of oral anticoagulant therapy. Clin Chem 2005; 51: 561-8. My favorite reference on specimen management is Adcock-Funk DM, Lippi G, Favaloro EJ. Quality standards for sample processing, transportation, and storage in hemostasis testing. Semin Thrombos Hemostas 2012; 38: 576–85. I hope the guideline and references help convince your coordinators. Geo.