In vitro stability of free prostate-specific antigen (PSA) and prostate-specific antigen (PSA) complexed to α1-antichymotrypsin in blood samples

Stability of total and free prostate specific antigen in serum submitted to intermittent cold storage conditions

“…The RT in our study, however, varied between 18°C and 28°C due to the fact that the air conditioners were turned off on weekends to save electricity in a country dealing with power crisis. Piironen et al (17) showed that room temperatures higher than 22°C might accelerate the decay of PSA-F. Our results are consistent with this finding since the PSA-F showed significant change (P= 0.0000) after one day of storage at RT. Previous studies on archival samples were performed by measuring the PSA just once after thawing the serum that has been stored frozen for a certain period of time.…”

“…Although testing the stability at RT was not one of the main objectives of our study, and knowing that serum should never be stored at RT, we did it as a way to test if the immunoreactivity of the archival serum used in our study was lost during the five month storage period. Earlier studies of PSA stability were carried out at room temperatures of approximately 22°C (14,(16)(17). The RT in our study, however, varied between 18°C and 28°C due to the fact that the air conditioners were turned off on weekends to save electricity in a country dealing with power crisis.…”

“…Therefore, PSA values should be interpreted with caution when the samples have been stored in such detrimental conditions. Stability of PSA stored at various conditions and length of time has been investigated before but in cases the samples were stored at stable temperatures (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). To our knowledge, there is no previous work pertaining to interrupted power supply (and therefore unstable storage temperatures).…”

Long-term stability of alpha-1-antichymotrypsin complexed form of prostate specific antigen

“…The instability of free PSA is presumably due to complexing of free PSA with alpha-2-macroglobulin or other serum substances. 21,24 In contrast to these reports, other studies have demonstrated stability of complexed PSA in serum and plasma under various storage conditions. Piironen et al 24 reported good stability of PSA-ACT in serum and plasma after 1 week at 4 C and after multiple freeze-thaw cycles at À20 C. Espana et al 25 reported PSA-ACT in Figure 1 18 months stability of cPSA.…”

“…The most pronounced decreases were observed for free PSA, an observation that has been con®rmed by others. 22,24 Arcangeli et al 20 found a signi®cant change from baseline level for free PSA when sera were stored at À20 C compared with À70 C. Over 2 weeks, however, no signi®cant changes were observed for total PSA. Additionally, Woodrum 21 found free PSA values decreased approximately 0.4% per month when stored at À70 C for periods of up to 1 y.…”