J Lab Med Qual Assur.  2013 Dec;35(2):122-132.

Long-Term Stability of Selected Serum Biomarkers in Leftover Samples

• Park BG
• Ihm C
• Sohn YH
• Choi EH

Abstract

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 -70degrees 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.

Keyword

Protein Stability; Enzyme Stability; Serum markers; Blood serum

MeSH Terms

Alanine Transaminase
Antigens, Surface
Arthritis, Rheumatoid
Aspartate Aminotransferases
Bias (Epidemiology)
Biomarkers*
C-Reactive Protein
Chemistry
Creatinine
Delivery of Health Care
Electrolytes
Enzyme Stability
Hepatitis B virus
Humans
Immunoassay
Indicators and Reagents
Insulin
Methods
Protein Stability
Reference Values
Serum
Thyrotropin
Alanine Transaminase
Antigens, Surface
Aspartate Aminotransferases
C-Reactive Protein
Creatinine
Electrolytes
Indicators and Reagents
Insulin
Thyrotropin