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KMID : 0985420130350020122
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Laboratory Medicine and Quality Assurance
2013 Volume.35 No. 2 p.122 ~ p.132
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Long-Term Stability of Selected Serum Biomarkers in Leftover Samples
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Park Borae-G
Ihm Chun-Hwa
Sohn Yong-Hak
Choi Eun-Hye
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Abstract
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Background: The purpose of this study was to assess the quality of long-term-stored leftover blood samples, and to evaluate the long-term stability of selected serum biomarkers such as proteins, enzymes, electrolytes, and tumour markers.
Methods: Stored blood samples were transferred to our biobank after being used to conduct tests for routine medical examinations in one health care institution, and were preserved at or below -70°C for 4 years. We analysed 24 biomarkers whose levels had been reported 4 years ago and tested them using the same analyser, reagents, and methods by utilizing an ADVIA Centaur Immunoassay System (Siemens Healthcare Diagnostics, USA) or an ADVIA 2400 Chemistry System (Siemens, USA).
Results: A total of 15 out of the 24 tested biomarkers showed significant differences in paired Student t-tests (P<0.01). Among them, 5 biomarkers (free T3, free T4, thyroid stimulating hormone, carcino-embryonic antigen, and alpha feto-protein) showed significant differences and high correlation coefficients (R2>0.975). Two biomarkers, creatinine and rheumatoid arthritis factor, showed no significant differences but were poorly correlated with previously analysed data. Aspartate aminotransferase, alanine aminotransferase, hepatitis B virus (HBV) surface antigen, and insulin levels were discordant according to their reference ranges. A total of 3 biomarkers, C-reactive protein, cancer antigen 125, and HBV surface antibody, showed no significant differences and good correlations without discordant data.
Conclusions: Our findings showed that long-term storage for more than 4 years can result in a considerable bias for variable biomarkers. Only 3 of the 24 biomarkers evaluated were found to be stable biomarkers. Long-term storage of leftover samples is not recommended for most chemical analyses.
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KEYWORD
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Protein Stability, Enzyme Stability, Serum markers, Blood serum
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