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Evaporation of serum after long-term biobank storage : A chemical analysis of maternal serum from a large Danish pregnancy screening registry

Uldbjerg, Cecilie S. ; Sørensen, Karina M. ; Lindh, Christian H. LU orcid ; Rantakokko, Panu ; Hauser, Russ ; Juul, Anders ; Andersson, Anna-Maria and Bräuner, Elvira V. (2023) In PLoS ONE 18(10 October).
Abstract

Background Relying on freezer stored biospecimens is preferred in epidemiolocal studies exploring environmental pregnancy exposures and later offspring health. Storage duration may increase the pre-analytical variability, potentially adding measurement uncertainty. We investigated evaporation of maternal serum after long-term biobank storage using ions (sodium, Na+; chloride, Cl-) recognized for stability and relatively narrow normal biological reference ranges in human serum. Methods A chemical analysis study of 275 biobanked second trimester maternal serum from a large Danish pregnancy screening registry. Serum samples were collected between 1985–1995 and stored at -20°C. Ion concentrations were quantified with... (More)

Background Relying on freezer stored biospecimens is preferred in epidemiolocal studies exploring environmental pregnancy exposures and later offspring health. Storage duration may increase the pre-analytical variability, potentially adding measurement uncertainty. We investigated evaporation of maternal serum after long-term biobank storage using ions (sodium, Na+; chloride, Cl-) recognized for stability and relatively narrow normal biological reference ranges in human serum. Methods A chemical analysis study of 275 biobanked second trimester maternal serum from a large Danish pregnancy screening registry. Serum samples were collected between 1985–1995 and stored at -20°C. Ion concentrations were quantified with indirect potentiometry using a Roche Cobas 6000 analyzer and compared according to storage time and normal biological ranges in second trimester. Ion concentrations were also compared with normal biological variation assessed by baseline Na+ and Cl- serum concentrations from a separate cohort of 24,199 non-pregnant women measured before freezing with the same instrument. Results The overall mean ion concentrations in biobanked serum were 147.5 mmol/L for Na+ and 109.7 for Cl-. No marked linear storage effects were observed according to storage time. Ion concentrations were consistently high across sampling years, especially for specific sampling years, and a relatively large proportion were outside respective normal ranges in second trimester: 38.9% for Na+ and 43.6% for Cl-. Some variation in concentrations was also evident in baseline serum used as quality controls. Conclusions Elevated ion concentrations suggest evaporation, but independent of storage duration in the present study (27–37 years). Any evaporation may have occurred prior to freezer storage or during the first 27 years. Other pre-analytical factors such as low serum volume have likely influenced the concentrations, particularly given the high within year variability. Overall, we consider the biobanked serum samples internally comparable to enable their use in epidemiological studies.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
PLoS ONE
volume
18
issue
10 October
article number
e0293527
publisher
Public Library of Science (PLoS)
external identifiers
  • scopus:85175272556
  • pmid:37883412
ISSN
1932-6203
DOI
10.1371/journal.pone.0293527
language
English
LU publication?
yes
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Publisher Copyright: © 2023 Uldbjerg et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
id
e62e4f5f-51e8-4c96-b3ec-c78d9bc3bcf5
date added to LUP
2023-12-13 14:43:02
date last changed
2024-12-21 10:03:32
@article{e62e4f5f-51e8-4c96-b3ec-c78d9bc3bcf5,
  abstract     = {{<p>Background Relying on freezer stored biospecimens is preferred in epidemiolocal studies exploring environmental pregnancy exposures and later offspring health. Storage duration may increase the pre-analytical variability, potentially adding measurement uncertainty. We investigated evaporation of maternal serum after long-term biobank storage using ions (sodium, Na<sup>+</sup>; chloride, Cl<sup>-</sup>) recognized for stability and relatively narrow normal biological reference ranges in human serum. Methods A chemical analysis study of 275 biobanked second trimester maternal serum from a large Danish pregnancy screening registry. Serum samples were collected between 1985–1995 and stored at -20°C. Ion concentrations were quantified with indirect potentiometry using a Roche Cobas 6000 analyzer and compared according to storage time and normal biological ranges in second trimester. Ion concentrations were also compared with normal biological variation assessed by baseline Na<sup>+</sup> and Cl<sup>-</sup> serum concentrations from a separate cohort of 24,199 non-pregnant women measured before freezing with the same instrument. Results The overall mean ion concentrations in biobanked serum were 147.5 mmol/L for Na<sup>+</sup> and 109.7 for Cl<sup>-</sup>. No marked linear storage effects were observed according to storage time. Ion concentrations were consistently high across sampling years, especially for specific sampling years, and a relatively large proportion were outside respective normal ranges in second trimester: 38.9% for Na<sup>+</sup> and 43.6% for Cl<sup>-</sup>. Some variation in concentrations was also evident in baseline serum used as quality controls. Conclusions Elevated ion concentrations suggest evaporation, but independent of storage duration in the present study (27–37 years). Any evaporation may have occurred prior to freezer storage or during the first 27 years. Other pre-analytical factors such as low serum volume have likely influenced the concentrations, particularly given the high within year variability. Overall, we consider the biobanked serum samples internally comparable to enable their use in epidemiological studies.</p>}},
  author       = {{Uldbjerg, Cecilie S. and Sørensen, Karina M. and Lindh, Christian H. and Rantakokko, Panu and Hauser, Russ and Juul, Anders and Andersson, Anna-Maria and Bräuner, Elvira V.}},
  issn         = {{1932-6203}},
  language     = {{eng}},
  number       = {{10 October}},
  publisher    = {{Public Library of Science (PLoS)}},
  series       = {{PLoS ONE}},
  title        = {{Evaporation of serum after long-term biobank storage : A chemical analysis of maternal serum from a large Danish pregnancy screening registry}},
  url          = {{http://dx.doi.org/10.1371/journal.pone.0293527}},
  doi          = {{10.1371/journal.pone.0293527}},
  volume       = {{18}},
  year         = {{2023}},
}