The effects of transport temperature and time on routine and specialized coagulation assays
Coagulation laboratories have largely stopped transporting whole blood specimens on ice, due to adverse effects on factor VIII, von Willebrand factor, and the prothrombin time. However, it is unknown whether ice should be required or avoided for other coagulation assays. Furthermore, the amount of time that specimens remain stable during transportation at room temperature (RT) is also largely unknown for many coagulation tests. Therefore, this study investigated specimen stability on ice and RT for a comprehensive panel of coagulation tests. One tube of whole blood from each volunteer (n = 22) was centrifuged immediately (time 0), one was stored for 4 h on ice, and one was stored for 4 h at RT before centrifugation. Among time 0, 4 h on ice, and 4 h at RT samples, no statistically significant differences were found for fibrinogen, activated protein C resistance, thrombin time, reptilase time, antithrombin activity, chromogenic protein C, factor XII, and antiplasmin activity. Prothrombin time, activated partial thromboplastin time, factors IX, XI, protein S activity, and plasminogen activity showed statistically, but not clinically, significant differences. On ice, the only analytes that showed clinically significant changes (≥6.0% from time 0) were factors VII, VIII, von Willebrand factor antigen, and ristocetin cofactor, which were 14.0% higher, and 19.2, 9.5, and 18.8% lower than time 0, respectively. At RT, all analytes were stable except factor VIII was 9.4% lower than time 0. Only factors II, V, X, and PTT-LA lupus anticoagulant showed a possible slight benefit from ice, but the statistically significant differences were not clinically significant. Ice did not substantially benefit any of the coagulation assays. All tests were stable at RT, except more study is needed regarding factor VIII.