Effects of storage and thawing conditions on coagulation testing

IntroductionCurrent recommendations for coagulation testing storage and thawing are based on historical studies that were performed using unbuffered 3.8% sodium citrate. We sought to measure the effects of freezing and thawing conditions 3.2% buffered sodium citrate plasma samples that have been stored in vials with either snap or sealed screw tops, frozen in -70 degrees C freezer or dry ice and thawed either capped or uncapped. MethodsShed blood samples were pooled and then aliquoted into four snap top and four screw tops vials. Half the vials were stored in a -70 degrees C freezer, and half on dry ice for at least 16h. Afterwards, half the frozen samples were thawed in 37 degrees C waterbath capped, and other half were thawed capped. After thawing cycles, samples were tested for PT, activated partial thromboplastin time (APTT), fibrinogen, D-dimer, factor assays, von Willebrand factor activity, plasminogen, antithrombin, protein C and lupus anticoagulant. ResultsProthrombin time, APTT, factor X, and lupus anticoagulant testing were affected by all vials, freezing and thawing conditions, whereas fibrinogen, D-dimer, von Willebrand activity or protein C were not affected by any vial, freezing or storage condition. ConclusionsStorage vials, freezing and thawing condition affect coagulation testing, although these differences may not be clinically significant.