Research article: Evaluation of the Effects of Freeze-Thaw Cycles on the Stability of Diabetes-Related Metabolic Biomarkers in Plasma Samples
Rebekka Gerwig, Frederikke Høgh, Joachim Størling, Katja Kemp Jacobsen
Int. J. Bio. Lab. Sci 2022(11)1:10-17【PDF】


Background: Repeatedly freezing and thawing of samples can affect the stability of biomarkers in plasma samples. There is a lack of studies reporting how these preanalytical factors affect the stability of diabetes-related metabolic biomarkers. This study investigated the effects of repeated freeze/thaw cycles (FTC) on the analysis of insulin, c-peptide, glucagon, total glucagon like peptide-1 (GLP-1), total glucose-dependent insulinotropic polypeptide (GIP), leptin and polypeptide YY (PYY).
Material and Methods: Plasma was prepared from blood samples collected from 10 healthy individuals. Each plasma sample was divided into 3 aliquots. An aliquot from each sample was analyzed immediately after preparation. The remaining aliquots were exposed to 3 and 5 repeated FTC. Samples were measured using a MESO Quickplex SQ 120 from Meso Scale Diagnostics LLC. (MSD) and the U-Plex Diabetes Combi 1 (hu) panel kit from MSD.
Results: The concentrations of GIP, GLP-1, insulin and PYY were statistical significantly affected by repeated FTC. After 5 FTC, the concentration of GIP was increased by 44 %, GLP-1 by 35 % and PYY by 22 %. There were no significant changes in the concentrations of glucagon, c-peptide and leptin after repeated FTC.
Conclusions: GIP, GLP-1 and PYY were significantly affected by repeated FTC. The concentration of these markers increased by 22-44 % with repeated FTC. Hence, repeated FTC can cause significant changes in the concentrations of the biomarkers. Our results suggest that caution should be exercised when comparing results of biomarkers between plasma samples that have been subject to FTC.


Key words: Preanalytical, laboratory test, plasma, freezing and thawing.

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