Journal Information
Journal ID (publisher-id): BM
Journal ID (nlm-ta): Biochem Med
Title: Biochemia Medica
Abbreviated Title: Biochem. Med.
ISSN (print): 1330-0962
ISSN (electronic): 1846-7482
Publisher: Croatian Society of Medical Biochemistry and Laboratory Medicine
Article Information
Copyright: 2016, Croatian Society of Medical Biochemistry
Date received: 05 January 2016
Date accepted: 29 July 2016
Publication date (print and electronic): 15 October 2016
Volume: 26
Issue: 3
Pages: 346-352
Publisher ID: bm-26-346
DOI: 10.11613/BM.2016.038
The influence of sample freezing at – 80 °C for 2–12 weeks on glycated haemoglobin (HbA1c) concentration assayed by HPLC method on Bio-Rad D-10® auto analyzer
Author notes:
Corresponding author: bergmann@vp.pl
Introduction
The aim of the study was to evaluate the effect of a single freeze/thaw cycle on HbA1c concentrations measured by commercially available HPLC method.
Materials and methods
Study included 128 whole blood samples collected from diabetic patients (N = 60) and healthy volunteers (N = 68). HbA1c concentrations were measured in fresh blood samples. Then samples were frozen at - 80 °C for up to 12 weeks. HbA1c was assayed by ion-exchange HPLC method on Bio-Rad D-10® analyzer. Variables were compared using Wilcoxon and ANOVA Kruskal-Wallis tests. Bias between HbA1c measured in fresh and frozen samples was calculated. The comparability of HbA1c concentrations was assessed by Bland-Altman plot.
Results
Median (IQR) HbA1c concentration was 45.3 (36.6–61.2) mmol/mol for fresh and 45.3 (36.6–60.6) mmol/mol for frozen/thawed samples. No significant difference in HbA1c concentrations was found comparing fresh and frozen/thawed samples (P = 0.070) in the whole group, as well as in healthy and diabetic subjects. The median calculated bias between fresh and frozen/thawed samples was 0% in whole group and healthy subjects, and 1.19% in diabetic patients. No significant difference was found between the biases according to baseline HbA1c values (P = 0.150). The Bland-Altman plot analysis showed a positive bias of 0.4% (95% CI: - 2.8 - 3.7%), which indicates high compliance between HbA1c values and no relevant influence of sample freezing on clinical significance of HbA1c measurement.
Keywords: glycated haemoglobin; diabetes; sample storage; high performance liquid chromatography; preanalytical phase
