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New developments in the standardization of total prostate-specific antigen
B G Blijenberg1, B N Storm, B D Van Zelst
1Department of Clinical Chemistry, University Hospital Rotterdam, The Netherlands. blijenberg@ckcl.azr.nl
Clinical Biochemistry
|January 19, 2000
Summary
Calibration differences were found between three new total prostate-specific antigen (PSA) assays. These assays, even with improved methods, do not provide interchangeable PSA results for clinical use.
Area of Science:
- Clinical Chemistry
- Biomarker Assay Development
- Prostate Cancer Diagnostics
Background:
- Accurate measurement of total prostate-specific antigen (PSA) is crucial for prostate cancer diagnosis and management.
- Recent advancements have introduced new assays for total PSA quantification.
Purpose of the Study:
- To analytically evaluate the calibration and performance of three recently launched total PSA assays: IMx Total PSA (Abbott), Elecsys PSA (Roche), and IMMULITE 3rd Generation PSA (DPC).
Main Methods:
- Assessed accuracy using two reference materials: Stanford 90:10 PSA Calibrator and Certified Reference Material 613 Prostate-Specific Antigen.
- Analyzed dilutions of reference materials and clinical specimens from prostate cancer and benign prostate hyperplasia patients.
- Compared assay results using samples from an ongoing prostate cancer screening study.
Main Results:
- All assays performed within 10% of calculated values with the Stanford Calibrator.
- Only IMx Total PSA closely matched the CRM Calibrator; IMMULITE differed by ~40% and Elecsys by ~18%.
- Statistically significant differences were observed between IMMULITE-IMx and IMMULITE-Elecsys assay combinations using clinical specimens, though less pronounced at lower PSA levels (<5.0 microg/L).
Conclusions:
- Analytical discrepancies exist among the evaluated total PSA assays when using different reference preparations.
- Despite methodological improvements, total PSA results from these assays are not interchangeable in a clinical setting.
- The clinical implications of these assay variations require further investigation.