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Background: Carbohydrate antigen 19-9 (CA19-9) is usually synthesized by pancreatic and bile duct cells and is present in small amounts in serum. During the period of tumor disease, its serum level significantly increases, and it is the most widely used serum tumor marker for diagnosis and monitoring therapy of pancreatic cancer.
Methods: We reported a case of abnormal elevation of serum CA19-9. Considering the possibility of detection interference, we used heterophilic antibody blocking analysis, detection by different analysis systems, and polyethylene glycol (PEG) precipitation to evaluate the reliability of abnormally elevated CA19-9 concentration.
Results: Repeated measurements on the Roche Cobas 8000 system of another hospital significantly reduced the CA19-9 concentration, as did PEG precipitation. Therefore, the abnormally elevated level of CA19-9 in this patient is considered to be pseudoelevation caused by interferences.
Conclusions: We suggest considering the presence of detection interference in cases with elevated CA19-9 levels but no related clinical manifestations to prevent false positives. PEG precipitation may be a simple and feasible solution to eliminate interference.
DOI: 10.7754/Clin.Lab.2023.230723
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