Abstract: Objective To explore the effects of three conditions of not taking calcium, taking calcium gluconate orally, and taking calcium lactate granules orally on blood Ca²⁺, PTH and adverse reactions of blood donors with fixed platelets donors, and to compare which calcium is better. Methods From July to September 2020, 35 volunteers (20 males and 15 females) were recruited from the fixed blood donor population at our center to participate in three sets of trials:The first group of experiments was a control group, which did not supplement calcium before platelet collection;The second group was supplemented with 10% Calcium gluconate oral liquid 20 minutes before collection (after sampling);The third group supplemented calcium lactate granules 20 minutes before harvest (after sampling).In each of the three experiments, 5ml of whole blood samples were collected for the detection of blood Ca²⁺ and PTH at sampling time (20 minutes before collection), needle insertion time (0 minutes after collection), middle school stage (20 minutes after collection), and later stage of collection (40 minutes after collection).Compare the trend of changes in blood Ca²⁺ and serum PTH values among three groups, and explore the effect of calcium agents. Results The change in blood Ca²⁺ of donors over time was significant（F=101.979,P<0.001）,the inter group effect was not significant（F=0.059,P=0.943>0.05）; The change in serum PTH over time was significant（F=495.834,P<0.001）,the inter group effect was not significant（F=1.241,P=0.294>0.05）;There was a negative correlation between blood Ca²⁺ and PTH values with changes in blood collection time.Both calcium agents reduce the probability of citric acid reaction.（P<0.05）Conclusion Regardless of whether preventive calcium supplementation was used or what type of calcium supplementation was used, the blood Ca²⁺ in blood donors could remain stable under the action of PTH.Preventive calcium supplements could reduce the risk of citric acid.

Key words: Apheresis Platelets, Calcium, Blood Ca²⁺, PTH, Citrate reaction