[Influence of serum storage on the laboratory results of prostate-specific antigen].

Objective: To investigate the influence of serum storage on the laboratory results of serum T-PSA, F-PSA and FPSA%.

Methods: Using automated chemiluminescence, we detected and compared the values of serum T-PSA, F-PSA and F-PSA% in the serum stored in different conditions.

Results: When the serum was stored at 4 degrees C or at the room temperature (22 - 26 degrees C), FPSA was unstable as compared with T-PSA. Compared with the initial value, after 4 hours at the room temperature, F-PSA was decreased to (0.392 +/- 0.246) microg/L (P < 0.01), while T-PSA and F-PSA% to (1.522 +/- 1.085) microg/L and (25.03 +/- 5.94)%, respectively, with no significant difference; after 8 hours at the room temperature, T-PSA and F-PSA were reduced to (1.513 +/- 1.083) and (0.389 +/- 0.247) microg/L (P < 0.05 and P < 0.01). At 4 degrees C, T-PSA, F-PSA and F-PSA% were decreased to (9.418 +/- 7.965) microg/L, (2.168 +/- 1.558) micro/L and (26.6 +/- 6.63)%, respectively, after 2 days (P < 0.05), and to (9.203 +/- 7.736) microg/L, (2.047 +/- 1.478) microg/L and (25.64 +/- 6.56)% after 1 week (P < 0.01). At -40 degrees C, T-PSA, F-PSA and F-PSA% were (4.532 +/- 4.393) microg/L, (1.178 +/- 1.034) microg/L and (24.45 +/- 8.81)% after 4 weeks. When the serum was stored at -40 degrees C and after 3 freeze-thaws, F-PSA and T-PSA were (5.982 +/- 5.314) and (1.341 +/- 1.029) microg/L, respectively, with no significant difference from the initial values.

Conclusion: Different conditions of serum storage have different influences on the laboratory results of serum TPSA, F-PSA and F-PSA%, more on F-PSA than on T-PSA, while F-PSA% is relatively stable. At -40 degrees C, T-PSA and F-PSA may remain stable for a month at least. Repeated freeze-thaws of the serum do not affect the laboratory results of F-PSA and T-PSA.