The Effect of Pre-Analytical Conditions on Blood Metabolomics in Epidemiological Studies

Abstract

Serum and plasma are commonly used in metabolomic-epidemiology studies. Their metabolome is susceptible to differences in pre-analytical conditions and the impact of this is unclear. Participant-matched EDTA-plasma and serum samples were collected from 37 non-fasting volunteers and profiled using a targeted nuclear magnetic resonance (NMR) metabolomics platform (n = 151 traits). Correlations and differences in mean of metabolite concentrations were compared between reference (pre-storage: 4 °C, 1.5 h; post-storage: no buffer addition delay or NMR analysis delay) and four pre-storage blood processing conditions, where samples were incubated at (i) 4 °C, 24 h; (ii) 4 °C, 48 h; (iii) 21 °C, 24 h; and (iv) 21 °C, 48 h, before centrifugation; and two post-storage sample processing conditions in which samples thawed overnight (i) then left for 24 h before addition of sodium buffer followed by immediate NMR analysis; and (ii) addition of sodium buffer, then left for 24 h before NMR profiling. We used multilevel linear regression models and Spearman’s rank correlation coefficients to analyse the data. Most metabolic traits had high rank correlation and minimal differences in mean concentrations between samples subjected to reference and the different conditions tested, that may commonly occur in studies. However, glycolysis metabolites, histidine, acetate and diacylglycerol concentrations may be compromised and this could bias results in association/causal analyses.

NMR Metabolite Profiles in Male Meat-Eaters, Fish-Eaters, Vegetarians and Vegans, and Comparison with MS Metabolite Profiles

“…Samples were non-fasted and were not cooled during transport to the laboratory, which may have affected the results of the NMR metabolomics assay [ 41 , 42 ], albeit studies exploring the potential impact of pre-processing conditions on the specific metabolites measured using the Nightingale platform are scarce. One study has reported that most of the metabolites measured using the Nightingale platform in non-fasted serum samples were not materially affected by delaying processing for 48 h at 21 °C (experimental condition; conditions similar to those in the current study) compared to processing within 1.5 h at 4 °C (reference condition) [ 42 ]. For metabolites consistently showing up as different between diet groups in the current analysis, rank correlations between metabolite concentrations in samples kept at the experimental versus the reference condition were 0.7 or above, except for, tyrosine ( r = 0.6) and lipid traits in small HDL (ranging from 0.6 and 0.7).…”

Discovery of predictors of sudden cardiac arrest in diabetes: rationale and outline of the RESCUED (REcognition of Sudden Cardiac arrest vUlnErability in Diabetes) project

“…However, previous research with this platform has observed that most metabolites (especially lipid related) are minimally affected by the prestorage and poststorage conditions tested. 41 Although we have data of many patients at our disposition, prediction of a complex and multicausal phenomenon like SCA might demand even bigger numbers.…”

Associations between Blood Metabolic Profile at 7 Years Old and Eating Disorders in Adolescence: Findings from the Avon Longitudinal Study of Parents and Children

“…Fatty acids were modelled in original units and as ratios (expressed in %) to total fatty acids. Details of this platform and its use in epidemiological studies have been described elsewhere [32,33,34,35,36]. In addition, we calculated the phenylalanine/tyrosine ratio as it was shown to be a marker of catabolism in individuals with anorexia nervosa [37,38].…”