Woodrum D, York L
Department of Research and Development, Hybritech Incorporated, San Francisco, California 92196-9006, USA.
Urology. 1998 Aug;52(2):247-51. doi: 10.1016/s0090-4295(98)00156-3.
To investigate the stability of free and total prostate-specific antigen (PSA) in serum stored at -20 degrees C and -70 degrees C for 2 years.
Fresh blood from 29 patients was drawn and allowed to clot at room temperature. Serum was prepared by centrifugation 1 hour later and tested to determine the free and total PSA levels. Samples were aliquoted, frozen at -20 degrees C or -70 degrees C, and monitored for long-term stability over the course of 2 years.
On average, 91% of the free PSA, 92% of the total PSA, and 89% of the percent free PSA values were recovered after 2 years of storage at -20 degrees C; and 96% of the free PSA, 101% of the total PSA, and 95% of the percent free PSA values were recovered after 2 years of storage at -70 degrees C. Seventy percent of the samples stored at -20 degrees C and 100% of the samples stored at -70 degrees C showed no statistically significant decline in free PSA values over the 2-year period. Only one total PSA sample (-20 degrees C) showed a statistically significant loss after 2 years of storage.
Our results suggest that samples stored frozen for up to 2 years at -70 degrees C should give acceptable percent free PSA results.
研究游离前列腺特异性抗原（PSA）和总前列腺特异性抗原在-20℃和-70℃储存2年的血清中的稳定性。
采集29例患者的新鲜血液，使其在室温下凝固。1小时后通过离心制备血清，并检测游离和总PSA水平。将样本分装，在-20℃或-70℃冷冻，并在2年的时间内监测其长期稳定性。
在-20℃储存2年后，平均91%的游离PSA、92%的总PSA和89%的游离PSA百分比值得以回收；在-70℃储存2年后，96%的游离PSA、101%的总PSA和95%的游离PSA百分比值得以回收。在-20℃储存的样本中有70%以及在-70℃储存的样本中有100%在2年期间游离PSA值无统计学显著下降。仅一个总PSA样本（-20℃）在储存2年后显示有统计学显著损失。
我们的结果表明，在-70℃冷冻储存长达2年的样本应能给出可接受的游离PSA百分比结果。
