[Stability of blood coagulation factors in plasma frozen 6 and 18 hours after blood collection].

In 50 plasma samples flash frozen at -40 degrees C within 6 h and in 50 samples flash frozen within 18 h after phlebotomy, both coagulation factors II, V, VII, VIII, IX and X as well as AT III, APTT and Quick were measured. Only factor VIII in 18-h plasma showed an average decrease from 0,99 IU/ml to 0,85 IU/ml, i. e. 15% compared to 6-h plasma. None of the other coagulation factors or parameters exhibited any change beyond normal ranges. Furthermore, 150 6-h and 150 18-h plasma samples were taken from routine production and after thawing were tested for factor VIII- and factor-V activity. In a long-term study following a one year's storage at -30 degrees C of 30 samples of 6-h plasma and 30 samples of 18-h plasma, a decrease was found with factor VIII from 0,97 IU/ml to 0,93 IU/ml in 6 h-plasma and from 0,90 IU/ml to 0,86 IU/ml in 18 h-plasma. Our results demonstrate that only minor differences exist in activity of coagulation factors of 6-h and 18-h plasma. Hence follows that by observing the instructions described, freezing must take place within an 18-h period after phlebotomy which thus allows 12 more hours for production without losses in activity.