Background: Coagulation factor assays are very important for diagnosing, treating, and monitoring inherited and acquired factor deficiencies. Appropriate pre-analytical storage conditions of citrate-anticoagulated plasma are essential for detection of coagulation factor activity. We aimed to investigate the effects of storage temperature and time on coagulation factor (F) II, FV, FVII, FX, FXI, and FXII activity up to 24 h and the effects of freeze-thaw times at -80 °C on factor activity.
Methods: Twenty-two blood samples were analyzed after storage for 0 (baseline), 2, 4, 6, 8, 12, and 24 h at 25 and 4 °C. Mean percent changes, numbers of samples with >10% changes, percent change trend plots, and difference plots were evaluated to determine clinically relevant differences.
Results: The acceptable storage times for FII coagulation activity (FII:C), FV:C, FVII:C, FX:C, FXI:C, and FXII:C were 24, 8, 8, 24, 12, and 12 h at 4 °C and 24, 4, 8, 8, 12, and 12 h at 25 °C, respectively. The acceptable freeze-thaw times for FII:C, FV:C, FVII:C, FX:C, FXI:C, and FXII:C were 2, 2, 3, 3, 2, and 1, respectively.
Conclusions: When factor activity cannot be determined within these acceptable timeframes, we recommend that plasma samples should be frozen and thawed at appropriate times for analysis.
Keywords: Coagulation factor; acceptable timeframes; freeze-thaw study; mean percent changes; storage temperature.