Automated Cobas Core PSA assays: Sensitive, precise, and specific measurement of PSA-Total and PSA-Total/PSA-Free ratio

We describe the analytical performance of the newly developed Roche Cobas C ore PSA Total EIA and the Cobas Core PSA Free ELA. The assays are designed for the random access immunochemistry analyzer Cobas Core. Both assays are highly precise (CVs < 4%) and highly sensitive (PSA Total: analytical sensi tivity < 0.02 ng/ml; PSA Free: < 0.01 ng/ml). The PSA Total EIA measures PS A-ACT and PSA free equimolarly. The assays are standardized against the ref erence material of the Stanford group and correlate very well with the desi gnated golden standard Hybritech Tandem-R assays. The high-dose-hook is bey ond 20000 ng/ml and 4500 ng/ml for the PSA Total and PSA Free assay, respec tively. In summary, the data indicate clearly the reliability of the measur ing system and the achievement of the demands of PSA diagnostics.