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The stability and variability of serum and plasma fibroblast growth factor-23 levels in a haemodialysis cohort

BACKGROUND: Serum fibroblast growth factor 23 (FGF-23) levels are markedly elevated in haemodialysis patients and have been linked to mortality outcomes. Small studies in health and chronic kidney disease, have demonstrated marked intra- and inter-individual variability in measured FGF-23 levels, an...

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Autores principales: Damasiewicz, Matthew J., Lu, Zhong X., Kerr, Peter G., Polkinghorne, Kevan R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6236962/
https://www.ncbi.nlm.nih.gov/pubmed/30428848
http://dx.doi.org/10.1186/s12882-018-1127-7
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author Damasiewicz, Matthew J.
Lu, Zhong X.
Kerr, Peter G.
Polkinghorne, Kevan R.
author_facet Damasiewicz, Matthew J.
Lu, Zhong X.
Kerr, Peter G.
Polkinghorne, Kevan R.
author_sort Damasiewicz, Matthew J.
collection PubMed
description BACKGROUND: Serum fibroblast growth factor 23 (FGF-23) levels are markedly elevated in haemodialysis patients and have been linked to mortality outcomes. Small studies in health and chronic kidney disease, have demonstrated marked intra- and inter-individual variability in measured FGF-23 levels, and variable degradation in serum as compared to plasma samples. In end-stage kidney disease (ESKD), the intra- and inter-individual variability of FGF-23 levels, and the optimal collection methods remain poorly characterized. In this study we assessed the variability of FGF-23 levels in a cohort of stable haemodialysis patients. Secondly, in a subset of patients, we assessed the effects of different collection methods on measured FGF-23 levels. METHODS: To assess the variability of FGF-23, pre-dialysis blood samples were collected over 3 consecutive weeks from 75 haemodialysis patients. The effects of different specimen collection methods were examined in a subset of patients (n = 23), with pre-dialysis blood collected into different tubes: plain (serum), EDTA (plasma) and EDTA with the addition of a protease inhibitor (EDTA-PI). All analyses were performed in the main cohort and repeated in each subgroup. Variability over a 3-week period was assessed using repeated measures ANOVA and random effects linear regression models. Intra-class correlation coefficients were calculated to assess agreement, and coefficients of variation were calculated to assess intra- and inter-individual variability. RESULTS: Over the 3-week study period the mean FGF-23 levels were not significantly different in the serum (p = 0.26), EDTA (p = 0.62) and EDTA-PI (p = 0.55) groups. FGF-23 levels demonstrated marked intra- and inter-individual variability with a CV of 36 and 203.2%, respectively. In the subgroup analysis, the mean serum FGF-23 levels were significantly lower than the EDTA (p < 0.001) or EDTA-PI (p < 0.001) groups, however there was no difference in mean FGF-23 levels between EDTA and EDTA-PI (p = 0.54). CONCLUSIONS: The measured FGF-23 levels were significantly lower in serum as compared to plasma, and the addition of a protease inhibitor did not confer an additional benefit. Importantly in this cohort of ESKD patients, FGF-23 levels showed marked intra- and inter-individual variability. The routine measurement of FGF-23 in ESKD remains challenging, however this study suggests the plasma is the optimal collection method for FGF-23 analysis.
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spelling pubmed-62369622018-11-23 The stability and variability of serum and plasma fibroblast growth factor-23 levels in a haemodialysis cohort Damasiewicz, Matthew J. Lu, Zhong X. Kerr, Peter G. Polkinghorne, Kevan R. BMC Nephrol Research Article BACKGROUND: Serum fibroblast growth factor 23 (FGF-23) levels are markedly elevated in haemodialysis patients and have been linked to mortality outcomes. Small studies in health and chronic kidney disease, have demonstrated marked intra- and inter-individual variability in measured FGF-23 levels, and variable degradation in serum as compared to plasma samples. In end-stage kidney disease (ESKD), the intra- and inter-individual variability of FGF-23 levels, and the optimal collection methods remain poorly characterized. In this study we assessed the variability of FGF-23 levels in a cohort of stable haemodialysis patients. Secondly, in a subset of patients, we assessed the effects of different collection methods on measured FGF-23 levels. METHODS: To assess the variability of FGF-23, pre-dialysis blood samples were collected over 3 consecutive weeks from 75 haemodialysis patients. The effects of different specimen collection methods were examined in a subset of patients (n = 23), with pre-dialysis blood collected into different tubes: plain (serum), EDTA (plasma) and EDTA with the addition of a protease inhibitor (EDTA-PI). All analyses were performed in the main cohort and repeated in each subgroup. Variability over a 3-week period was assessed using repeated measures ANOVA and random effects linear regression models. Intra-class correlation coefficients were calculated to assess agreement, and coefficients of variation were calculated to assess intra- and inter-individual variability. RESULTS: Over the 3-week study period the mean FGF-23 levels were not significantly different in the serum (p = 0.26), EDTA (p = 0.62) and EDTA-PI (p = 0.55) groups. FGF-23 levels demonstrated marked intra- and inter-individual variability with a CV of 36 and 203.2%, respectively. In the subgroup analysis, the mean serum FGF-23 levels were significantly lower than the EDTA (p < 0.001) or EDTA-PI (p < 0.001) groups, however there was no difference in mean FGF-23 levels between EDTA and EDTA-PI (p = 0.54). CONCLUSIONS: The measured FGF-23 levels were significantly lower in serum as compared to plasma, and the addition of a protease inhibitor did not confer an additional benefit. Importantly in this cohort of ESKD patients, FGF-23 levels showed marked intra- and inter-individual variability. The routine measurement of FGF-23 in ESKD remains challenging, however this study suggests the plasma is the optimal collection method for FGF-23 analysis. BioMed Central 2018-11-14 /pmc/articles/PMC6236962/ /pubmed/30428848 http://dx.doi.org/10.1186/s12882-018-1127-7 Text en © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research Article
Damasiewicz, Matthew J.
Lu, Zhong X.
Kerr, Peter G.
Polkinghorne, Kevan R.
The stability and variability of serum and plasma fibroblast growth factor-23 levels in a haemodialysis cohort
title The stability and variability of serum and plasma fibroblast growth factor-23 levels in a haemodialysis cohort
title_full The stability and variability of serum and plasma fibroblast growth factor-23 levels in a haemodialysis cohort
title_fullStr The stability and variability of serum and plasma fibroblast growth factor-23 levels in a haemodialysis cohort
title_full_unstemmed The stability and variability of serum and plasma fibroblast growth factor-23 levels in a haemodialysis cohort
title_short The stability and variability of serum and plasma fibroblast growth factor-23 levels in a haemodialysis cohort
title_sort stability and variability of serum and plasma fibroblast growth factor-23 levels in a haemodialysis cohort
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6236962/
https://www.ncbi.nlm.nih.gov/pubmed/30428848
http://dx.doi.org/10.1186/s12882-018-1127-7
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