Analytical performance of the Tandem®-R free PSA immunoassay measuring free prostate-specific antigen

Abstract

The analytical performance of the Tandem®-R free PSA assay available from Hybritech Inc. was evaluated. Comparison of recoveries of purified free (unbound) prostate-specific antigen (PSA) diluted in female serum in the Tandem-R free PSA assay and the Tandem-R (total) PSA assay demonstrated a link in calibration between the assays and an accurate determination of percent free PSA. The cross-reactivity of the assay to purified PSA-α1- antichymotrypsin was determined to be <1%. The minimum-detectable concentration was <0.05 μg/L. The within-run and between-day CVs were ≤5% for samples with >0.3 μg/L free PSA. Dilution and recovery showed no significant deviations from linearity across the assay range. The assay was insensitive to interference from blood components. The Tandem-R free PSA kit was shown to be an accurate, precise, and reliable assay for the measurement of free PSA.