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The Diagnostic Trap: When PSA Results Mislead - A Case Report
Johan Baden Birk-Korch1, Christine Vestergaard Madsen2, Tobias Kromann-Tofting1
1Department of Biochemistry and Immunology, Lillebaelt Hospital, University Hospital of Southern Denmark, Vejle, Denmark.
Case Reports in Oncology
|August 29, 2025
Summary
Assay interference can cause falsely low prostate-specific antigen (PSA) levels in metastatic prostate cancer patients. Vigilance and laboratory collaboration are crucial for accurate diagnosis and treatment monitoring.
Area of Science:
- Clinical Chemistry
- Oncology
- Laboratory Medicine
Background:
- Immunoassays are vital in clinical diagnostics but susceptible to interference, leading to inaccurate results.
- Prostate-specific antigen (PSA) is a key biomarker for prostate cancer monitoring.
- Assay interference can manifest as falsely elevated or suppressed analyte concentrations.
Observation:
- A patient with metastatic prostate cancer presented with unexpectedly low plasma PSA levels.
- Discrepancies in PSA measurements between two different laboratory assays (Abbott Architect and Roche Cobas e602) were noted.
- The lower PSA values were traced to assay interference with the Abbott Architect assay.
Findings:
- Analytical interference in immunoassays can lead to clinically misleading results.
- Falsely low PSA concentrations were observed in a patient with metastatic castration-resistant prostate cancer due to assay interference.
- The discrepancy prompted further investigation, revealing the underlying analytical issue.
Implications:
- Highlights the critical need for clinician-laboratory collaboration to address unexpected diagnostic findings.
- Emphasizes the importance of considering analytical interference when laboratory results contradict clinical presentations.
- Underscores the necessity for ongoing efforts to minimize assay interference and ensure diagnostic accuracy in cancer biomarker testing.
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