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Variability of urinary cadmium excretion in spot urine samples, first morning voids, and 24 h urine in a healthy non-smoking population: Implications for study design

Akerstrom, Magnus; Barregard, Lars; Lundh, Thomas LU and Sallsten, Gerd (2014) In Journal of Exposure Science & Environmental Epidemiology 24(2). p.171-179
Abstract
When selecting the least biased exposure surrogate, for example, the concentration of a biomarker in a urine sample, information on variability must be taken into consideration. We used mixed-effects models to estimate the variability and determinants of urinary cadmium (U-Cd) excretion using spot urine samples collected at six fixed times during 2 days about 1 week apart, from 24 healthy non-smokers. The urine samples were analysed for U-Cd, the concentrations were adjusted for dilution, and the excretion rates were calculated. Between-individual variability dominated the total variability for most measures of U-Cd excretion, especially for 24h urine and first morning samples. The U-Cd excretion showed a circadian rhythm during the day,... (More)
When selecting the least biased exposure surrogate, for example, the concentration of a biomarker in a urine sample, information on variability must be taken into consideration. We used mixed-effects models to estimate the variability and determinants of urinary cadmium (U-Cd) excretion using spot urine samples collected at six fixed times during 2 days about 1 week apart, from 24 healthy non-smokers. The urine samples were analysed for U-Cd, the concentrations were adjusted for dilution, and the excretion rates were calculated. Between-individual variability dominated the total variability for most measures of U-Cd excretion, especially for 24h urine and first morning samples. The U-Cd excretion showed a circadian rhythm during the day, and time point of sampling was a significant factor in the mixed-effects models, thus a standardised sampling time, such as first morning urine samples, needs to be applied. Gender, urinary flow rate, age, and urinary protein excretions were also significant determinants for U-Cd excretion. The choice of biomarker for U-Cd excretion was found to be more important in individually-based studies of exposure-response relationships than in studies of comparing Cd levels of groups. When planning a study, this variability of U-Cd in spot samples must be acknowledged. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
variability, spot urine, urinary excretion, cadmium, 24h urine, study, design
in
Journal of Exposure Science & Environmental Epidemiology
volume
24
issue
2
pages
171 - 179
publisher
Nature Publishing Group
external identifiers
  • wos:000331596000009
  • scopus:84896706810
ISSN
1559-064X
DOI
10.1038/jes.2013.58
language
English
LU publication?
yes
id
088c60bb-5285-4729-8226-0386e79bdbeb (old id 4363702)
date added to LUP
2014-04-07 09:21:30
date last changed
2017-10-01 04:13:06
@article{088c60bb-5285-4729-8226-0386e79bdbeb,
  abstract     = {When selecting the least biased exposure surrogate, for example, the concentration of a biomarker in a urine sample, information on variability must be taken into consideration. We used mixed-effects models to estimate the variability and determinants of urinary cadmium (U-Cd) excretion using spot urine samples collected at six fixed times during 2 days about 1 week apart, from 24 healthy non-smokers. The urine samples were analysed for U-Cd, the concentrations were adjusted for dilution, and the excretion rates were calculated. Between-individual variability dominated the total variability for most measures of U-Cd excretion, especially for 24h urine and first morning samples. The U-Cd excretion showed a circadian rhythm during the day, and time point of sampling was a significant factor in the mixed-effects models, thus a standardised sampling time, such as first morning urine samples, needs to be applied. Gender, urinary flow rate, age, and urinary protein excretions were also significant determinants for U-Cd excretion. The choice of biomarker for U-Cd excretion was found to be more important in individually-based studies of exposure-response relationships than in studies of comparing Cd levels of groups. When planning a study, this variability of U-Cd in spot samples must be acknowledged.},
  author       = {Akerstrom, Magnus and Barregard, Lars and Lundh, Thomas and Sallsten, Gerd},
  issn         = {1559-064X},
  keyword      = {variability,spot urine,urinary excretion,cadmium,24h urine,study,design},
  language     = {eng},
  number       = {2},
  pages        = {171--179},
  publisher    = {Nature Publishing Group},
  series       = {Journal of Exposure Science & Environmental Epidemiology},
  title        = {Variability of urinary cadmium excretion in spot urine samples, first morning voids, and 24 h urine in a healthy non-smoking population: Implications for study design},
  url          = {http://dx.doi.org/10.1038/jes.2013.58},
  volume       = {24},
  year         = {2014},
}