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The association between outdoor temperature during the past weeks and current fluid homeostasis

Enhörning, Sofia LU ; Melander, Olle LU orcid ; Elmståhl, Sölve LU ; Engström, Gunnar LU ; Pihlsgård, Mats LU and Timpka, Simon LU orcid (2026) In Epidemiology 37(4). p.447-455
Abstract

BACKGROUND: It remains unclear why cool temperatures cause more persistent adverse health effects compared to hot weather. Fluid homeostasis may constitute a causal link between past temperatures and adverse health effects. In this study we investigated the association between past outdoor temperatures and current fluid homeostasis.

METHODS: We studied participants from five cohorts during three decades in Sweden (total n=29,755, age 18-86 years, 50.4% women). We quantified fluid homeostasis through indicators of hormonal regulation (vasopressin biomarker plasma copeptin), urine concentration (urine osmolality), and replenishment of fluid loss (total water intake) and related these parameters to past outdoor temperatures (21 days)... (More)

BACKGROUND: It remains unclear why cool temperatures cause more persistent adverse health effects compared to hot weather. Fluid homeostasis may constitute a causal link between past temperatures and adverse health effects. In this study we investigated the association between past outdoor temperatures and current fluid homeostasis.

METHODS: We studied participants from five cohorts during three decades in Sweden (total n=29,755, age 18-86 years, 50.4% women). We quantified fluid homeostasis through indicators of hormonal regulation (vasopressin biomarker plasma copeptin), urine concentration (urine osmolality), and replenishment of fluid loss (total water intake) and related these parameters to past outdoor temperatures (21 days) using distributed non-linear lag models.

RESULTS: Past temperatures were non-linearly associated with current copeptin and urine osmolality.Cool temperatures during days and weeks prior contributed to distinct patterns of high copeptin with concomitant influence on urine osmolality. Overall, a scenario of temperatures of 0 °C for 21 days showed 14.9% (95% confidence interval 11.5-18.3%) higher copeptin levels compared to reference temperatures of 14.3 °C for 21 days. Associations between copeptin and warm temperatures were less complex and of shorter duration, linking elevated temperatures within 24 hours with higher copeptin compared to the reference temperature.

CONCLUSIONS: Alterations in human fluid homeostasis may partly explain the observed link between moderately cool outdoor temperatures and adverse health effects weeks later. If so, avoiding altered water balance through moderately increased water intake might mitigate adverse health effects of cool weather.

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Please use this url to cite or link to this publication:
author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Epidemiology
volume
37
issue
4
pages
447 - 455
publisher
Wolters Kluwer
external identifiers
  • pmid:41790995
ISSN
1531-5487
DOI
10.1097/EDE.0000000000001968
language
English
LU publication?
yes
additional info
Copyright © 2026 The Author(s). Published by Wolters Kluwer Health, Inc.
id
062fbd93-b147-484f-b128-f3db8ff1c2ce
date added to LUP
2026-05-29 14:55:23
date last changed
2026-06-01 08:03:40
@article{062fbd93-b147-484f-b128-f3db8ff1c2ce,
  abstract     = {{<p>BACKGROUND: It remains unclear why cool temperatures cause more persistent adverse health effects compared to hot weather. Fluid homeostasis may constitute a causal link between past temperatures and adverse health effects. In this study we investigated the association between past outdoor temperatures and current fluid homeostasis.</p><p>METHODS: We studied participants from five cohorts during three decades in Sweden (total n=29,755, age 18-86 years, 50.4% women). We quantified fluid homeostasis through indicators of hormonal regulation (vasopressin biomarker plasma copeptin), urine concentration (urine osmolality), and replenishment of fluid loss (total water intake) and related these parameters to past outdoor temperatures (21 days) using distributed non-linear lag models.</p><p>RESULTS: Past temperatures were non-linearly associated with current copeptin and urine osmolality.Cool temperatures during days and weeks prior contributed to distinct patterns of high copeptin with concomitant influence on urine osmolality. Overall, a scenario of temperatures of 0 °C for 21 days showed 14.9% (95% confidence interval 11.5-18.3%) higher copeptin levels compared to reference temperatures of 14.3 °C for 21 days. Associations between copeptin and warm temperatures were less complex and of shorter duration, linking elevated temperatures within 24 hours with higher copeptin compared to the reference temperature.</p><p>CONCLUSIONS: Alterations in human fluid homeostasis may partly explain the observed link between moderately cool outdoor temperatures and adverse health effects weeks later. If so, avoiding altered water balance through moderately increased water intake might mitigate adverse health effects of cool weather.</p>}},
  author       = {{Enhörning, Sofia and Melander, Olle and Elmståhl, Sölve and Engström, Gunnar and Pihlsgård, Mats and Timpka, Simon}},
  issn         = {{1531-5487}},
  language     = {{eng}},
  month        = {{03}},
  number       = {{4}},
  pages        = {{447--455}},
  publisher    = {{Wolters Kluwer}},
  series       = {{Epidemiology}},
  title        = {{The association between outdoor temperature during the past weeks and current fluid homeostasis}},
  url          = {{http://dx.doi.org/10.1097/EDE.0000000000001968}},
  doi          = {{10.1097/EDE.0000000000001968}},
  volume       = {{37}},
  year         = {{2026}},
}