Woodrum D, French C, Shamel L B
Hybritech, Inc., San Diego, California 92196-9006, USA.
Urology. 1996 Dec;48(6A Suppl):33-9. doi: 10.1016/s0090-4295(96)00607-3.
Four studies were conducted to characterize the stability of free and total prostate specific antigen (PSA) under various sample collection and storage conditions.
In the first study, fresh blood from 11 patients was drawn and allowed to clot at room temperature (RT). Serum was prepared by centrifugation 1, 3, 5, or 8 hours after the blood draw and tested to determine the free and total PSA levels. In the second study, serum specimens from 12 individuals were stored at RT or 4 degrees C and were tested on days 0, 1, 2, and 7. In the third study, four fresh serum samples were subjected to five freeze-thaw cycles and tested after each cycle. In the fourth study, 29 fresh samples were aliquoted, frozen at -20 degrees C or -70 degrees C, and monitored for long-term stability.
Approximately 1% of the free PSA was lost per hour of clotting time. Between 2% and 3% of the free PSA was lost per day of storage at 4 degrees C or 23 degrees C. About 0.9% of the free PSA was lost per month of storage at -20 degrees C compared with about 0.4% per month at -70 degrees C. Total PSA appeared to be stable throughout these studies.
Our results suggest that routine serum preparation and refrigerated storage of samples for up to 24 hours is acceptable for the measurement of both free and total PSA. Samples that are to be retained for longer than 24 hours should be frozen. Samples stored for extended periods should be kept at -70 degrees C.
进行了四项研究，以表征游离和总前列腺特异性抗原（PSA）在各种样本采集和储存条件下的稳定性。
在第一项研究中，采集了11名患者的新鲜血液，使其在室温（RT）下凝固。采血后1、3、5或8小时通过离心制备血清，并进行检测以确定游离和总PSA水平。在第二项研究中，将12名个体的血清标本储存在室温或4℃下，并在第0、1、2和7天进行检测。在第三项研究中，对四个新鲜血清样本进行五次冻融循环，并在每个循环后进行检测。在第四项研究中，将29个新鲜样本进行分装，在-20℃或-70℃下冷冻，并监测其长期稳定性。
每小时的凝血时间会导致约1%的游离PSA损失。在4℃或23℃储存时，每天约有2%至3%的游离PSA损失。在-20℃储存时，每月约有0.9%的游离PSA损失，而在-70℃时每月约为0.4%。在这些研究中，总PSA似乎是稳定的。
我们的结果表明，对于游离和总PSA的测量，常规血清制备和将样本冷藏储存长达24小时是可以接受的。要保留超过24小时的样本应冷冻。长期储存的样本应保存在-70℃。
