Different free prostate-specific antigen to total prostate-specific antigen ratios using three detecting systems.

BACKGROUND: Prostate-specific antigen (PSA) is used as an indicative marker of a pathologic condition of the prostate, and the ratio of free PSA (fPSA) to total PSA (tPSA) helps to distinguish benign prostatic hyperplasia (BPH) from prostate cancer (PCa). In this study, we present some reversed ratios of fPSA to tPSA and analyze the possible mechanism.

METHODS: Using the UniCel DxI800 Access Immunoassay System, eight reversed fPSA to tPSA ratios were obtained, and then these samples were retested with an Abbott Architect i2000 Immunoassay Analyser and Cobas e602.

RESULTS: Four of the eight reversed ratios kept a ratio >1 using Abbott Architect i2000, and seven of them turned into a ratio <1 using Cobas e602.

CONCLUSION: In consideration of the assay these three detecting systems apply, the possible reason of the reversed ratios can be heterophile antibodies. To get accurate reason, further study is required.