Pre-analytical stability of coagulation parameters in plasma stored at room temperature

Haemostasis testing is influenced by many pre-analytical variables, such as storage time and temperature, which can affect the stability of coagulation factors and influence the results of coagulation assays. We investigated the stability of haemostasis tests after storage of aliquoted plasma at RT, including the variability of measurement principle and reagent used for determination.

Blood samples from 20 healthy volunteers were obtained, processed to PPP and aliquoted. Aliquots were stored at RT for 0 hour, 2 hours, 4 hours, 6 hours, 8 hours, 12 hours, 24 hours and 48 hours. PT, aPTT, fibrinogen, D-Dimers and coagulation factors (FII, FV, FVII, FX, FVIII, FIX, FXI, FXII) were determined by STA-R Max^® and ACL-TOP^® . VWF:Ag and vWF:RCo were determined by AcuStar^® . Clinically relevant changes, compared to the initial measurement, were denoted as a percentage change of > 10% according to the 99% CI.

For both analysers, a clinically relevant change of > 10% was observed for FV after 2 hours, FVIII after 4 hours and for aPTT, FII, FVII, FX and FXII after 48 hours of storage at RT. Statistically significant, but no clinically relevant differences were observed after 48-hours storage for PT, fibrinogen and FIX. D-Dimers, FXI, vWF:Ag and vWF:RCo were found stable up to 48 hours at RT.

Overall, compared to the limits given by the current CLSI guidelines, for most coagulation parameters investigated in this study a longer storage period could be accepted. Time intervals for FVIII and FV dosage were shorter than recommended by the CLSI guidelines. For PT determination, our findings were consistent.