A comparative study of the effects of temperature, time and factor VIII assay type on factor VIII activity in cryoprecipitate in Iran

In Iran, cryoprecipitate is an important plasma product to provide coagulation factors such as factor VIII (FVIII) in patients with factor VIII deficiency. FVIII is one of the labile coagulation factors and as such is also used as a quality marker of fresh-frozen plasma and cryoprecipitate. It is, therefore, important to optimise plasma production in order to prevent a reduction of FVIII activity. In this study we assessed the effect of temperature, time and FVIII assay type on FVIII activity in cryoprecipitate produced in Iran. Ninety-six whole blood units were kept at two different temperatures (48 units kept at 1-6 °C and 48 kept at 20-24 °C) for periods of 4, 6, 8 or 10 hours before plasma freezing. FVIII activity was then measured by both chromogenic and one-stage clotting assays. At both temperatures, FVIII activity in plasma prepared after 8 and 10 hours was lower than that in plasma prepared after 4 and 6 hours. A significant decrease of FVIII activity was not seen in samples kept for 4 and 6 hours. Compared to storage between 1-6 °C, storage at 20-24 °C appears to cause a reduction in FVIII activity. There was a significant difference in apparent FVIII activity measured by the one-stage clot-based and chromogenic assays. In Iran, to improve cryoprecipitate quality, freezing should begin within 6 hours after donation and whole blood should be kept at 1-6 °C until the plasma can be frozen. In this study although a good correlation was seen between the results of the one-stage clot-based and chromogenic assays for measuring FVIII activity in cryoprecipitate, the absolute values were significantly different.