Mean tPSA values were measured at 4, 8, 24 and 48 h with values of 7.9, 8.1, 7.8 and 8.0 μg/L, respectively. Total PSA ( tPSA) and free PSA (f PSA) values were determined using the Tosoh AIA 1800 assay (Tokyo, Japan). Blood samples were taken from 20 male patients in four VACUETTE ® Serum Separator tubes (Greiner-Bio-One, Austria) and stored at room temperature (22 Â☌) for different time intervals (4, 8, 24, 48 h) before being centrifuged and analyzed. We aimed to replicate storage conditions at room temperature and see if prolonged storage affected total and free PSA values. In 2010, an estimated 476,076 total PSA tests were performed in Ireland, at a cost of €3.6 million with the majority ordered by general practitioners. Stability and accuracy of total and free PSA values in samples stored at room temperature.įorde, J C Blake, O Crowley, V E Lynch, T H Further harmonization efforts are required in order to obtain a complete clinical concordance. We have shown significant discordances between assays included in this study despite advances in standardization conducted in the last years.
At a critical concentration of 20 and 25 %, ADVIA Centaur XP, ARCHITECT i2000, and IMMULITE 2000 assays exceeded the 10 % relative difference limit. For percent f PSA, at a critical concentration of 10 %, the 10 % relative difference limit was exceeded by IMMULITE 2000 assay. For tPSA, relative differences were more than 10 % at 0.2 μg/L for ARCHITECT i2000, and at a critical concentration of 3, 4, and 10 μg/L, the relative difference was exceeded by ADVIA Centaur XP and WHO-calibrated Access. Passing-Bablok analysis was performed for PSA, and percentage of f PSA with the Hybritech-calibrated access comparison assay. tPSA and f PSA were measured in Access using the Hybritech and WHO calibrators. In the present study, we tested 167 samples with tPSA concentrations of 0 to 20 μg/L using seven PSA and six f PSA commercial assays, including Access, ARCHITECT i2000, ADVIA Centaur XP, IMMULITE 2000, Elecsys, and Lumipulse G1200, in which we only measured tPSA. To characterize the current situation, it is necessary to know its impact in the critical cutoffs used in clinical practice.
The variability of total PSA ( tPSA) and free PSA (f PSA) results among commercial assays has been suggested to be decreased by calibration to World Health Organization (WHO) reference materials. Variability of assay methods for total and free PSA after WHO standardization.įoj, L Filella, X Alcover, J Augé, J M Escudero, J M Molina, R
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