Abstract.Factor V activity was assayed in routinely‐prepared fresh frozen plasma (FFP) and in frozen plasma, cryoprecipitate‐removed (FPCR). Mean activity in FFP within 1 week of preparation was 86%, but declined to 63% after 2 months of storage at ‐35°C. Within 1 week of preparation, FPCR factor V activity was 56%; there was little loss of activity during 3 months of freezer storage. The difference between FFP and FPCR is due to loss of factor V activity during the 24 h required for preparation of cryoprecipitate. The factor V activity of either FPCR or stored FFP is probably adequate to provide hemostatic levels in a patient who is severely deficient in fa
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