Study2021Open access

Effects of diet, habitual water intake and increased hydration on body fluid volumes and urinary analysis of renal fluid retention in healthy volunteers

Hahn RG

European journal of nutrition · 24 citations

How it was studied

Design
Controlled clinical trial (classified by our AI screen)
Studied in
People
Main outcome
Health markers and function

Who paid for it

Funding
Independent funding
Nonprofit
Robert J. Kleberg, Jr. and Helen C. Kleberg Foundation
University or hospital
Karolinska Institutet

Based on 2 listed funder(s) and full-text disclosure statement.

Publication

Published
2020-05-19 · Eur J Nutr · vol. 60 · issue 2 · pp. 691–702
Publisher
Springer Science+Business Media
Cited
32 citations · more than 86% of similar papers · 1.9× the field average
References
39 works
Access
Open access (hybrid journal) · CC-BY
Research areas
Thermoregulation and physiological responses · Body Composition Measurement Techniques · Electrolyte and hormonal disorders
Keywords
Morning, Urine, Body fluid, Fluid intake, Urine osmolality, Creatinine, Medicine, Body water, Population, Dehydration, Urine sample, Internal medicine, Animal science, Endocrinology, Chemistry, Physiology, Body weight, Biochemistry
MeSH
body water, humans, dehydration, urinalysis, diet, water-electrolyte balance, drinking, osmolar concentration, adult, healthy volunteers

1 author

From SE

  • Robert G. Hahn · correspondingKarolinska Institutet; Södertälje Sjukhus

Abstract

Purpose

To increase our knowledge about the causes and physiological consequences of concentrated urine, the relevance of which in the general population is uncertain.

Methods

Twenty healthy volunteers (mean age 42 years) recorded all intake of food and water for 2 weeks. During the 2nd week, they increased their daily consumption of water by 716 mL (32%). The volunteers delivered a 24-h and a morning urine sample for analysis of osmolality and creatinine during the first 4 days of both weeks, and a sample each time they voided on the other days. The water content of food and liquid was calculated and the body fluid volumes were measured by bioimpedance. Haemodynamic stability was assessed with the passive leg-raising test.

Results

There was a curvilinear correlation between the daily intake of water and biomarkers measured in the 24-h collection of urine (coefficient of determination 0.37-0.70). Habitual low intake of water was associated with larger body fluid volumes. The increased fluid intake during the 2nd week was best reflected in the 24-h collection (-15 and -20% for the osmolality and creatinine, respectively, P < 0.002), while morning urine and body fluid volumes were unchanged. Increased fluid intake improved the haemodynamic stability in volunteers with a low intake of water (< median), but only in those who had minimally concentrated morning urine.

Conclusions

The 24-h collection reflected recent intake of fluid, whereas the morning urine seemed to mirror long-term corrections of the fluid balance. Concentrated urine was associated with larger body fluid volumes.

Abstract via Europe PMC. Copyright remains with the authors or publisher (CC BY).

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