Reliability of Estimates of Serum Inorganic Iodine and Daily Fecal and Urinary Iodine Excretion from Single Casual Specimens

Vought, R. L.; London, William T.; Lutwak, Leo; Dublin, Thomas D.

doi:10.1210/jcem-23-12-1218

Cited by 88 publications

(40 citation statements)

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“…Moreover, and in contrast to 24 h iodine excretion, a single spot of urine does not represent the mean value of different iodine concentrations in several mictions over a 24 h period. For this reason I/24h is the gold standard of iodine supply, despite the fact that up to 10% of the daily iodine intake may leave the human body by fecal or perspiration losses (Vought et al, 1963). To our knowledge, this is the first methodological study on iodine based on repeated 24 h collections and spot samples in adult subjects allowing direct comparison between I/24h, I/ cr and I/L.…”

Section: Discussionmentioning

confidence: 99%

“…It is routinely evaluated via urinary excretion. In physiological conditions, losses by perspiration and feces are negligible (Follis et al, 1962;Vought et al, 1963) so that urinary iodine is regarded as a valuable index of iodine intake. Since its first description in 1937, the chemical analysis of iodide proposed by Sandell & Kolthoff (1937) was first applied to geological substrates such as rock, soil and water.…”

Section: Introductionmentioning

confidence: 99%

“…When precise 24 h urine collections could be obtained, iodine output was presented as an excretion in mg I/day or better mg I/24h. In field studies, quantification of iodine has been most often deduced from readily available spot samples and expressed as a concentration in mg I/g creatinine (mg I/g cr, mmol I/mmol cr) or, lately, in mg I/dL (Follis et al, 1962;Vought et al, 1963;Jolin & Escobar del Rey, 1965;Bourdoux et al, 1985;Bourdoux, 1988Bourdoux, , 1998Delange et al, 1997;Als et al, 2003). However, many authors still confusedly use the term excretion instead of concentration or try to simply extrapolate the former from the latter or report mean values for data that are not normally distributed.…”

Section: Introductionmentioning

confidence: 99%

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Quantification of urinary iodine: a need for revised thresholds

et al. 2003

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Objective: To compare different possibilities of reporting the iodine supply in the same urine samples. Indeed, in field studies, urinary iodine concentration (I/L: mg I/L, mmol I/L, I/creatinine: mg I/g creatanine, mmol I/mol creatinine) is more readily available than excretion (I/24h mg I/24 h, mmol I/24h). However, confusion exists regarding the comparability of iodine supply based upon I/L, I/creatinine and I/24h, which for decades have been regarded as biochemically equivalent. Design: We compared I/24h, I/L and I/creatinine in accurate 24 h collections of urine and I/L and I/creatinine in 47 spot urine samples. Patients: A total of 13 subjects (Bern n ¼ 7, Brussels n ¼ 6) collected a total of 110 precise 24 h urine collections (Bern n ¼ 63, Brussels n ¼ 47). The subjects from Brussels also took a spot sample at the beginning of each 24 h collection. Results: Iodine supply in both places was mildly deficient according to the criteria of WHO; all but one collection indicated an intake of 40.39 mmol I/24h (450 mg I/24h). The same data presented as I/creatinine (or I/L) indicated an iodine intake of o0.39 (o50 mg I/24h) in 5% (24%) of the samples in Bern and 23% (57%) in Brussels. Similar findings were observed for 47 spot samples. Whatever the cut-off selected, I/creatinine and I/L were systematically lower than I/24h (Po0.0002). Creatinine showed smaller CV than volume but did not perform better in defining iodine intake. Conclusion: Considering I/24h as a reference, both I/creatinine and I/L clearly underestimate the iodine intake in subjects with adequate proteoenergetic intake. The significant deviations observed illustrate the urgent need for establishing separate ranges for I/24h, I/creatinine and I/L. In population studies, these deviations might even be larger.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Quantification of urinary iodine: a need for revised thresholds

et al. 2003

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“…A 24 h urinary iodine excretion (UIE) is the most reliable index of iodine availability in a stated population and is universally employed in epidemiological studies on goiter and iodine deficiency disorders, since it corresponds to 95% of the dietary iodine intake (Vought et al, 1963;Als et al, 2003b). However, as it is difficult to obtain 24-h urine samples, single urine samples taken in the morning are generally used, and the iodine contents are given as a concentration (urinary iodine concentration, UIC, mg/l) or as an iodine-creatinine (I/Cr) ratio.…”

Section: Introductionmentioning

confidence: 99%

Restricted intraindividual urinary iodine concentration variability in nonfasting subjects

et al. 2005

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Objective: Individual urinary iodine concentration (UIC) reflects iodine intake over a short time prior to sampling. Since eating habits are relatively constant in single subjects, UIC should be relatively constant in a given individual. The aim of our study was to verify this hypothesis by assessing UIC in repeated single urine samples from a group of healthy subjects. Design and Setting: A prospective sequential investigation was performed in 131 volunteer health workers or students recruited in our University hospital. Interventions: Single urine samples were taken in a nonfasting state, between 0900 and 1100 hours. Group 1 was composed by 131 subjects who collected one urine sample. Group 2 was composed by 11 subjects of the group 1, who collected multiple repeated urine samples (as a whole 158 urine samples, mean 14 samples each). UIC mean7s.d., median and coefficient of variation (CV%) was measured in both groups. Results: Interindividual UIC variation was wide, UIC ranging from 21 to 382 mg/l, mean 136784 mg/l, median 124 mg/l, CV 62%. Also in the 11 subjects repeatedly sampling there were considerable differences among individual UIC average levels (ranging from 37715 to 221791 mg/l). However, in this second group, the intraindividual variation was considerably restricted (CV% 36).Conclusions: The present study shows that in a nonfasting state in mid-morning UIC is more stable from day to day in a single subject, depending on his eating habits, than in various subjects. Thus, a single urine sample even in nonfasting state may give some rough information about the individual's iodine status.

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“…A quantidade de iodo excretado por grama de creatinina em uma amostra urinária é representativa do total urinário excretado, desde que a excreção renal de creatinina não sofra grandes flutuações (20)(21)(22)(23). Apesar da creatinúria ter sido avaliada por nós, nas mesmas amostras, a relação iodúria/creatinúria não foi utilizada pois o coeficiente dessa relação não foi menor que a concentração de iodo urinário isolada (24).…”

Section: Methodsunclassified

Correlação entre níveis de iodúria e TSH colhido em cordão umbilical de recém-nascidos do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, São Paulo

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Maciel

Kunii

et al. 2005

Arq Bras Endocrinol Metab

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Correlation Between Urinary Iodine Levels and TSH of Umbilical Cord fromNewborns of the University Hospital at the School of Medicine from Ribeirão Preto, São Paulo. The safest and most efficient way to diagnose congenital hypothyroidism (CH) is through screening programs using serum thyroid stimulating hormone (TSH). CH occurs in one in 1:2,300 -1:5,000 births but higher rates are found in iodine-deficient areas. Iodine was measured in the urine of 141 newborns (87 males and 54 females) from Ribeirão Preto to complement the screening program developed by the School of Medicine of Ribeirão Preto (FMRP-USP) and Federal University of São Paulo (UNIFESP). TSH values did not disclose any case of CH, although we have seen an elevated ratio (0.96%) of calls for retests. The iodine urinary levels ranged from 2.1 to 194µg/l (mean 58.3±36.2µg/l). No differences between the levels of urinary iodine and gender or gestational ages were observed. A negative correlation between urinary iodine and TSH of blood from umbilical cord was found (r= -0.20, p= 0.02).

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Reliability of Estimates of Serum Inorganic Iodine and Daily Fecal and Urinary Iodine Excretion from Single Casual Specimens

Cited by 88 publications

References 2 publications

Quantification of urinary iodine: a need for revised thresholds

Quantification of urinary iodine: a need for revised thresholds

Restricted intraindividual urinary iodine concentration variability in nonfasting subjects

Correlação entre níveis de iodúria e TSH colhido em cordão umbilical de recém-nascidos do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, São Paulo

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