Plain English Summary
Background and study aims
Urinalysis (a test that evaluates a sample of urine) has been used to detect dehydration in sports medicine, but rarely in hospital patients. The kidneys hold onto water when a person is dehydrated, which can be detected by increasing osmolality (concentration of salts), urine-specific weight, darker urine colour, and a higher concentration of creatinine (a waste product from muscle activity). This approach could have a value in hospital care. The aim of this study is to investigate whether spot urine samples vary over the day and whether there is a relationship between dietary intake of water and how much the urine is concentrated.
Who can participate?
Hospital workers found to have concentrated or dilute urine when screened.
What does the study involve?
For the first week of the study, participants are asked to continue with their usual drinking habits and to keep a record of everything they eat and drink. They also provide urine samples daily which are assessed to detect dehydration. For the second week of the study, participants are asked to drink an additional 1.2 L of water every day. Throughout this time, participants record everything they eat and drink and provide urine samples every day. Before the study starts and then after the first and second week, participants undergo a medical examination in order to assess their general health.
What are the possible benefits and risks of participating?
Participants found to have concentrated urine at the start of the study may benefit from learning how much they should drink to have normally concentrated urine. There are no risks involved with participating.
Where is the study run from?
Södertälje Hospital (Sweden)
When is the study starting and how long is it expected to run for?
February 2016 to November 2017
Who is funding the study?
Mats Kleberg Foundation (Sweden)
Who is the main contact?
Professor Robert Hahn
Protocol no 1
Fluid retention in the normal population
1. Fluid retention in the normal population is caused by lack of sufficient water intake
2. Fluid retention can be reversed by increased water intake
Regional Ethics Board of Stockholm, 15/06/2016, ref: 2016/826-31
Primary study design
Secondary study design
Non randomised study
Patient information sheet
Not available in web format, please use the contact details below to request a patient information sheet
For the first week of the study participants are asked to continue their normal eating and drinking habits and also to record their dietary/fluid intake and provide daily urine samples. These urine samples are assessed for urine colour, osmolarity, specific weight and creatinine.
In the second week of the study, participants are asked to ingest an additional 1.2 L of water per day. During this time participants continue to record dietary/fluid intake and provide daily urine samples for uranalysis.
Before the study starts and at the end of the first week and second week, participants undergo a medical examination with heart auscultation, blood pressure, the passive leg test and bioimpedance analysis of the body fluid volumes.
Primary outcome measure
Composition of urine (urine colour, urinalysis of osmolality, specific weight, and creatinine) is assessed using urinalysis conducted on samples collected daily from baseline to the end of the second week.
Secondary outcome measures
1. Food and fluid intake throughout the study is assessed using food/fluid diaries throughout the both weeks of the study
2. Heart auscultation is assessed by a stethoscope at baseline and at 1 and 2 weeks
3. Blood pressure by Nexfin hemodynamic monitor at baseline and at 1 and 2 weeks
4. Passive leg test by Nexfin hemodynamic monitor at baseline and at 1 and 2 weeks
5. Bioimpednace for measurement of body fluid volumes at baseline and at 1 and 2 weeks
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Healthy hospital workers
2. Found after screening to have either concentrated urine or diluted urine
Target number of participants
Total final enrolment
Participant exclusion criteria
1. Medical disease requiring daily medication
2. Any kind of kidney disorder
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Research Unit House 18, 6th Floor Lagmansvägen 15
152 86 Södertälje
Mats Kleberg Foundation
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
The result is planned to be published in an international scientific journal.
IPD Sharing plan:
The datasets generated during and/or analysed during the current study are/will be available upon request from Professor Robert Hahn (email@example.com)
Intention to publish date
Participant level data
Available on request
Basic results (scientific)
2020 results in https://pubmed.ncbi.nlm.nih.gov/32430554/ (added 18/09/2020)