We evaluated the use of serum-concentration for early detection of PSA after radical prostatectomy (RP) to improve sensitivity of automated assays 4-fold. 600 sera after RP were lyophilisation-concentrated 2-, 3- and 4-fold and analysed in parallel both native and concentrated with 3 assays. Results were identical in the 3 assays in >90%, of the native and concentrated sera. However by concentration 8.32% (n=50) additional positive samples were identified. Positivity in concentrated serum precedes positivity in native serum by about 300 days. Concentration-induced supersensitive detection increases sensitivity of standard PSA assays. It is simple, reliable and easy to perform.

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