title: Vitamin K-dependent coagulation factors and fibrinogen levels in FFP remain stable upon repeated freezing and thawing.
abstract: BACKGROUND
  FFP is considered adequate for transfusion up to 24 hours after thawing and is currently used most often to replace deficient clotting factors, such as in warfarin overdose. We set to examine the levels of vitamin K-dependent factors (i.e., prothrombin, FVII, F IX, FX), as well as fibrinogen, upon twice freezing and thawing of FFP. If factor levels in refrozen FFP remain within normal limits, this component can possibly be transfused, thus avoiding wastage of precious blood components.
  
  
  METHODS
  Twenty units of FFP, five units of each blood group A, B, AB, and O, were thawed, and aliquots were taken for measurement of coagulation factors. The plasma units were then kept for 24 hours at 4 degrees C, at which point a second aliquot was taken, The remaining FFP units were refrozen and kept at -80 degrees C for 1 week. The above procedure was then repeated. Coagulation-factor activity and fibrinogen level were measured by the coagulation analyzer.
  
  
  RESULTS
  The mean levels of prothrombin, FVII, F IX, FX, and fibrinogen of each blood group (A, B, AB, and O) were calculated for each of four time points and found not statistically different (p > 0.05). Therefore, the rest of the analysis was done for all 20 FFP units as one group. The mean +/- SD levels of each coagulation factor at each time point demonstrated that all levels were within normal limits of all factors measured and that for none of the factors was there a significant decay of activity.
  
  
  CONCLUSIONS
  The levels of prothrombin, FVII, F IX, FX, and fibrinogen remain stable and adequate for transfusion in twice-thawed-and-refrozen FFP. This component can be safely used for transfusion as a source of vitamin K-dependent clotting factors and fibrinogen.
authors.affiliation: Blood Bank and Hematology, Tel Aviv, Sourasky, Medical, Center, Tel Aviv, Israel. obental@netvision.net.il
authors.forename: Ofira
authors.initials: O
authors.lastname: Ben-Tal
authors.forename: Ety
authors.initials: E
authors.lastname: Zwang
authors.forename: Roza
authors.initials: R
authors.lastname: Eichel
authors.forename: Tanya
authors.initials: T
authors.lastname: Badalbev
authors.forename: Mara
authors.initials: M
authors.lastname: Hareuveni
mesh_terms: D000017:ABO Blood-Group System; D001779:Blood Coagulation Factors / Q000032:analysis*; D015925:Cryopreservation; D004355:Drug Stability; D005164:Factor IX / Q000032:analysis; D005167:Factor VII / Q000032:analysis; D005170:Factor X / Q000032:analysis; D005340:Fibrinogen / Q000032:analysis*; D006358:Hot Temperature; D006801:Humans; D010949:Plasma / Q000737:chemistry*; D014812:Vitamin K / Q000494:pharmacology*
chemical_list: D000017:ABO Blood-Group System; D001779:Blood Coagulation Factors; D014812:Vitamin K; D005167:Factor VII; D005164:Factor IX; D005170:Factor X; D005340:Fibrinogen