Intraindividual variation in urinary iodine concentrations

Effect of adjustment on population distribution using two and three repeated spot urine collections

Karen Charlton, Marijka Batterham, Li Min Buchanan, Dorothy Mackerras

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Objectives: To determine the effect of adjustment for intraindividual variation on estimations of urinary iodine concentrations (UIC), prevalence of iodine deficiency and population distribution of iodine status.

Setting: 
Community-dwelling older adults from New South Wales, Australia.

Participants: 
84 healthy men and women aged 60–95 years were recruited prior to introduction of the mandatory iodine fortification programme.

Primary and secondary outcome measures:
 UIC data were collected from three spot urine samples, each 1 week apart. Repeated measures analysis of variance were determined between-person (sb) and total (sobs) SDs. Adjusted UIC values were calculated as ((person's UIC−group mean)×(sb/sobs))+group mean, and a corrected UIC distribution was calculated.

Results:
 The sb/sobs for using three samples and two samples were 0.83 and 0.79, respectively. Following adjustment for intraindividual variation, the proportion with UIC <50 μg/L reduced from 33% to 19%, while the proportion with UIC ≥100 μg/L changed from 21% to 17%. The 95th centile for UIC decreased from 176 to 136 μg/L. Adjustment by taking averages yielded a lesser degree of contraction in the distribution than the analysis of variance method.

Conclusions: 
The addition of information about intraindividual variability has potential for increasing the interpretability of UIC data collected to monitor the iodine status of a population.
Original languageEnglish
Article numbere003799
Pages (from-to)1-5
Number of pages5
JournalBMJ Open
Volume4
DOIs
Publication statusPublished - 2014

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Urine Specimen Collection
Iodine
Demography
Analysis of Variance
Independent Living
South Australia
New South Wales
Healthy Volunteers

Cite this

@article{94367af26994452c92d6446c074e67de,
title = "Intraindividual variation in urinary iodine concentrations: Effect of adjustment on population distribution using two and three repeated spot urine collections",
abstract = "Objectives: To determine the effect of adjustment for intraindividual variation on estimations of urinary iodine concentrations (UIC), prevalence of iodine deficiency and population distribution of iodine status.Setting: Community-dwelling older adults from New South Wales, Australia.Participants: 84 healthy men and women aged 60–95 years were recruited prior to introduction of the mandatory iodine fortification programme.Primary and secondary outcome measures: UIC data were collected from three spot urine samples, each 1 week apart. Repeated measures analysis of variance were determined between-person (sb) and total (sobs) SDs. Adjusted UIC values were calculated as ((person's UIC−group mean)×(sb/sobs))+group mean, and a corrected UIC distribution was calculated.Results: The sb/sobs for using three samples and two samples were 0.83 and 0.79, respectively. Following adjustment for intraindividual variation, the proportion with UIC <50 μg/L reduced from 33{\%} to 19{\%}, while the proportion with UIC ≥100 μg/L changed from 21{\%} to 17{\%}. The 95th centile for UIC decreased from 176 to 136 μg/L. Adjustment by taking averages yielded a lesser degree of contraction in the distribution than the analysis of variance method.Conclusions: The addition of information about intraindividual variability has potential for increasing the interpretability of UIC data collected to monitor the iodine status of a population.",
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author = "Karen Charlton and Marijka Batterham and Buchanan, {Li Min} and Dorothy Mackerras",
year = "2014",
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language = "English",
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pages = "1--5",
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Intraindividual variation in urinary iodine concentrations : Effect of adjustment on population distribution using two and three repeated spot urine collections. / Charlton, Karen; Batterham, Marijka; Buchanan, Li Min; Mackerras, Dorothy.

In: BMJ Open, Vol. 4, e003799, 2014, p. 1-5.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Intraindividual variation in urinary iodine concentrations

T2 - Effect of adjustment on population distribution using two and three repeated spot urine collections

AU - Charlton, Karen

AU - Batterham, Marijka

AU - Buchanan, Li Min

AU - Mackerras, Dorothy

PY - 2014

Y1 - 2014

N2 - Objectives: To determine the effect of adjustment for intraindividual variation on estimations of urinary iodine concentrations (UIC), prevalence of iodine deficiency and population distribution of iodine status.Setting: Community-dwelling older adults from New South Wales, Australia.Participants: 84 healthy men and women aged 60–95 years were recruited prior to introduction of the mandatory iodine fortification programme.Primary and secondary outcome measures: UIC data were collected from three spot urine samples, each 1 week apart. Repeated measures analysis of variance were determined between-person (sb) and total (sobs) SDs. Adjusted UIC values were calculated as ((person's UIC−group mean)×(sb/sobs))+group mean, and a corrected UIC distribution was calculated.Results: The sb/sobs for using three samples and two samples were 0.83 and 0.79, respectively. Following adjustment for intraindividual variation, the proportion with UIC <50 μg/L reduced from 33% to 19%, while the proportion with UIC ≥100 μg/L changed from 21% to 17%. The 95th centile for UIC decreased from 176 to 136 μg/L. Adjustment by taking averages yielded a lesser degree of contraction in the distribution than the analysis of variance method.Conclusions: The addition of information about intraindividual variability has potential for increasing the interpretability of UIC data collected to monitor the iodine status of a population.

AB - Objectives: To determine the effect of adjustment for intraindividual variation on estimations of urinary iodine concentrations (UIC), prevalence of iodine deficiency and population distribution of iodine status.Setting: Community-dwelling older adults from New South Wales, Australia.Participants: 84 healthy men and women aged 60–95 years were recruited prior to introduction of the mandatory iodine fortification programme.Primary and secondary outcome measures: UIC data were collected from three spot urine samples, each 1 week apart. Repeated measures analysis of variance were determined between-person (sb) and total (sobs) SDs. Adjusted UIC values were calculated as ((person's UIC−group mean)×(sb/sobs))+group mean, and a corrected UIC distribution was calculated.Results: The sb/sobs for using three samples and two samples were 0.83 and 0.79, respectively. Following adjustment for intraindividual variation, the proportion with UIC <50 μg/L reduced from 33% to 19%, while the proportion with UIC ≥100 μg/L changed from 21% to 17%. The 95th centile for UIC decreased from 176 to 136 μg/L. Adjustment by taking averages yielded a lesser degree of contraction in the distribution than the analysis of variance method.Conclusions: The addition of information about intraindividual variability has potential for increasing the interpretability of UIC data collected to monitor the iodine status of a population.

KW - iodine

KW - adjustment

KW - adult

KW - aged

KW - analysis of variance

KW - article

KW - Australia

KW - community

KW - controlled study

KW - female

KW - health program

KW - human

KW - iodine deficiency

KW - laboratory test

KW - major clinical study

KW - male

KW - medical information

KW - middle aged

KW - outcome assessment

KW - population distribution

KW - predictive value

KW - prevalence

KW - urinalysis

KW - very elderly

KW - demography

KW - procedures

KW - statistics and numerical data

KW - urine

KW - Aged

KW - Aged, 80 and over

KW - Demography

KW - Female

KW - Humans

KW - Iodine

KW - Male

KW - Middle Aged

KW - Urine Specimen Collection

U2 - 10.1136/bmjopen-2013-003799

DO - 10.1136/bmjopen-2013-003799

M3 - Article

VL - 4

SP - 1

EP - 5

JO - BMJ Open

JF - BMJ Open

SN - 2044-6055

M1 - e003799

ER -