METHODS: We collected the remaining plasma of 29 patients. The baseline of antithrombin, protein C, and protein S activity values were tested within 4 h. Then, each sample was sub-packaged into 4 EP tubes, and was stored at -20 °C for 3 days, -20 °C for 7 days, -80 °C for 3 days, and - 80 °C for 7 days, respectively. After thawing, samples were tested by two systems.
RESULTS: The percentage deviation of antithrombin and protein C activity assay was<10% compared with the initial values. Protein S activity showed a significant reduction in frozen plasma, with a deviation > 10%. Some samples, initially within the normal range, were classified as abnormal after freezing storage.
CONCLUSIONS: Our study indicated that antithrombin and protein C remain stable when stored at -20 °C or -80 °C in a week. We argued that Protein S activity is not stable in frozen plasma. The use of frozen-thawed plasma for PS activity assay may result in overdiagnosis of protein S deficiency.
方法:我们收集了29名患者的剩余血浆。抗凝血酶的基线,蛋白C,和蛋白质S活性值在4小时内进行测试。然后,每个样品被分装到4个EP管中,并在-20°C下储存3天,-20°C持续7天,-80°C持续3天,和-80°C持续7天,分别。解冻后,样品通过两个系统进行测试。
结果:与初始值相比,抗凝血酶和蛋白C活性测定的百分比偏差<10%。蛋白S活性在冷冻血浆中显示显著降低,偏差>10%。一些样品,最初在正常范围内,在冷冻储存后被归类为异常。
结论:我们的研究表明,抗凝血酶和蛋白C在-20°C或-80°C下储存一周时保持稳定。我们认为蛋白S活性在冷冻血浆中不稳定。使用冻融血浆进行PS活性测定可能会导致蛋白S缺乏症的过度诊断。