Abstract: Objective To investigate the effects of varying sodium citrate anticoagulant dosages on plasmapheresis plasma quality and donor parameters, thus establishing an evidence-based dosage regimen tailored for the Chinese plasma donor population. Methods An in vitro study was done involving 220 volunteer plasma donors, who were randomly assigned to four experimental groups. Each group received a different volume ratio of 4% sodium citrate anticoagulant to whole blood: 1∶18, 1∶20, 1∶22, and 1∶25. A control group used a standard anticoagulant-to-whole blood ratio of 1∶16. Two separate whole blood samples were collected from each donor; one was treated with the designated anticoagulant ratio while the other was treated with the control ratio (1∶16). Plasma was then isolated by centrifugation and analyzed for the following parameters: pH, conductivity, activated Partial Thromboplastin Time (APTT), prothrombin time (PT), coagulation factor Ⅷ (FⅧ) activity, coagulation factor Ⅸ (FⅨ) activity, fibrinogen (Fg) level, and total plasma protein content. Correlations between the anticoagulant dose (citrate-to-blood ratio) and each measured parameter were analyzed. Results No significant differences in pH or Fg levels were observed between any experimental group and the control group (all P>0.05). A slight decrease in conductivity (≤0.29 μs/cm) was noted in groups with an anticoagulant-to-blood ratio≤1∶25 compared to the control (1∶16). Although the mean values of plasma protein content, APTT, FⅧ activity, and FⅨ activity varied with the anticoagulant dilution ratio, all remained within their respective reference ranges. However, the mean PT fell below the reference range when the anticoagulant dilution ratio was≤1∶20. Within the tested range (1∶18 to 1∶25), the anticoagulant concentration showed no significant correlation with plasma protein content, pH, and Fg; a weak positive correlation with conductivity and APTT (r=0.264, P<0.01 and r=0.267, P<0.01, respectively); a moderate negative correlation with FⅧ and FⅨ activity (r=-0.417, P<0.01 and r=-0.358, P<0.01, respectively); and a strong positive correlation with PT (r=0.566, P<0.01). Conclusion Within the tested sodium citrate dilution ratio range of 1∶18 to 1∶25, adjustments in anticoagulant concentration had limited and manageable effects on plasma quality parameters but exerted measurable effects on donor coagulation function. These results indicate differential sensitivity of coagulation pathways to citrate anticoagulation. Considering the balance between coagulation function preservation and plasma component stability, a sodium citrate anticoagulant-to-blood ratio of 1∶20 represents a potential optimization threshold for plasmapheresis procedures. Nevertheless, the safety profile of this specific ratio, particularly concerning donor tolerance and citrate-related adverse events, requires further validation in subsequent clinical studies.

Key words: Plasma donor, Sodium citrate anticoagulant dosage, Plasma quality, Apheresis plasma