Hi George: We encountered a case recently where we were asked to perform coagulation testing on specimens collected in EDTA vacutainers. The patient was refusing to give more blood than already collected for further coagulation tests and the attending doctor requested us to perform the tests in the blood collected in EDTA vials. We refused considering the protocols to be followed for coagulation testing, but was wondering as to what difference the same would have made in the values if the tests were actually performed.The tests requested were PT , PTT , fibrinogen and factor VIII .
Thanks, Dr Siddhartha Sharma
Hello, Dr. Sharma, and thank you for your question. You were absolutely correct, you cannot generate accurate coagulation results from an EDTA specimen, a problem that occasionally affects reference laboratories. In particular the PT and PTT results are markedly prolonged, and factor levels are markedly reduced. The issue is addressed in Adcock-Funk DM, Lippi G, Favaloro EJ. Quality standards for sample processing, transportation, and storage in hemostasis testing. Semin Thromb Hemost 2012;38: 576–85, and is reflected in the CLSI H21-A5 standard. I hope this helps.