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Technical Note: Newly Reformulated Total and Free PSA Immunoassay on Cobas e411 Analyzer Is Virtually Free from
Anindita Ghosh1, Alejandra Russell2, Amitava Dasgupta3
1Department of Pathology and Laboratory Medicine, University of Texas McGovern Medical School at Houston, Houston, TX, USA.
Objective:
Total and free prostate specific antigens (PSA) have been used as diagnostic markers for monitoring progress of therapy in patients with prostate cancer as well as for screening purpose. Roche total and free PSA immunoassay utilizes biotinylated antibody in assay design. As a result, both assays are affected by elevated serum biotin levels. Recently, Roche reformulated these assays to reduce biotin interference. We evaluated biotin interference in these products.
Materials And Methods:
We prepared three serum pools with one pool containing high amount of total PSA. Then aliquots of each serum pool were further supplemented with various concentrations of biotin (100-1500 ng/mL) followed by measuring both total and free PSA using Roche total and free PSA immunoassay and Cobas e411 analyzer.
Results:
We observed no significant interference of biotin in both total and free PSA assays up to biotin concentration of 1200 ng/mL.
Conclusion:
We concluded that newly reformulated total and free PSA immunoassays are virtually free from biotin interference.
