Establishing reference intervals for urine and serum iodine levels: A nationwide multicenter study of a euthyroid Chinese population

Yu, Songlin; Wang, Danchen; Cheng, Xinqi; Zhang, Qiong; Wang, Mingxue; Guo, Haiyun; Yu, Benzhang; Zhang, Xiuming; Xia, Liangyu; Sun, Dandan; Cheng, Qian; Li, Pengchang; Yin, Yanzhen; Ma, Chaochao; Hou, Li’an; Zou, Yutong; Li, Honglei; Li, Dandan; Qiu, Ling; Ichihara, Kiyoshi

doi:10.1016/j.cca.2019.11.038

Cited by 19 publications

(16 citation statements)

References 23 publications

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“…Similar regional variations in iodine status were reported in three cities in Turkey whose population is mildly iodine deficient [32]. Also, regional variations in iodine status have been reported across four cities in China with evidence of adequate iodine status [66]. Although there is iodine adequacy on a population level in Canada, residents from Quebec City and Vancouver (~191 µg/day or 92.1 µg/L, n = 400) were at a 2.5-fold greater relative risk for iodine deficiency as compared to Hamilton and Ottawa (~269 µg/day or 124 µg/L, n = 400) after covariate adjustments and Bonferroni correction.…”

Section: Regional Variations In Iodine Deficiency Across Canada Modul...supporting

confidence: 73%

The Prevalence and Risk Factors Associated with Iodine Deficiency in Canadian Adults

et al. 2022

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Iodine is a trace micronutrient that is critical for normal thyroid function and human health. Inadequate dietary intake is associated with cognitive impairment, infertility, growth retardation and iodine deficiency disorders in affected populations. Herein, we examined the prevalence of iodine deficiency in adults (median age of 61 years) based on the analysis of 24 h urine samples collected from 800 participants in four clinical sites across Canada in the Prospective Urban and Rural Epidemiological (PURE) study. Urinary iodide together with thiocyanate and nitrate were measured using a validated capillary electrophoresis assay. Protective/risk factors associated with iodine deficiency were identified using a binary logistic regression model, whereas daily urinary iodine concentration (24 h UIC, μg/L) and urinary iodine excretion (24 h UIE, μg/day) were compared using complementary statistical methods with covariate adjustments. Overall, our Canadian adult cohort had adequate iodine status as reflected by a median UIC of 111 μg/L with 11.9% of the population <50 μg/L categorized as having moderate to severe iodine deficiency. Iodine adequacy was also evident with a median 24 h UIE of 226 μg/day as a more robust metric of iodine status with an estimated average requirement (EAR) of 7.1% (< 95 μg/day) and a tolerable upper level (UL) of 1.8% (≥1100 μg/day) based on Canadian dietary reference intake values. Participants taking iodine supplements (OR = 0.18; p = 6.35 × 10−5), had greater 24 h urine volume (OR = 0.69; p = 4.07 × 10−4), excreted higher daily urinary sodium (OR = 0.71; p = 3.03 × 10−5), and/or were prescribed thyroxine (OR = 0.33; p = 1.20 × 10−2) had lower risk for iodine deficiency. Self-reported intake of dairy products was most strongly associated with iodine status (r = 0.24; p = 2.38 × 10−9) after excluding for iodine supplementation and T4 use. Participants residing in Quebec City (OR = 2.58; p = 1.74 × 10−4) and Vancouver (OR = 2.54; p = 3.57 × 10−4) were more susceptible to iodine deficiency than Hamilton or Ottawa. Also, greater exposure to abundant iodine uptake inhibitors from tobacco smoking and intake of specific goitrogenic foods corresponded to elevated urinary thiocyanate and nitrate, which were found for residents from Quebec City as compared to other clinical sites. Recent public health policies that advocate for salt restriction and lower dairy intake may inadvertently reduce iodine nutrition of Canadians, and further exacerbate regional variations in iodine deficiency risk.

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Section: Regional Variations In Iodine Deficiency Across Canada Modul...supporting

confidence: 73%

The Prevalence and Risk Factors Associated with Iodine Deficiency in Canadian Adults

et al. 2022

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“…However, collection of multiple 24 h UICs would be even more of a burden to the patient than a single collection and be subject to collection error including missed urine samples. The difficulty of collecting 24 h urines and additional limitations [ 25 , 29 , 45 , 46 , 47 , 48 , 49 ] that include being cumbersome to the patient and being subject to within-day hydration and iodine intake changes prompted us to evaluate other potential biomarkers of iodine status (serum iodine and Tg) in the current study.…”

Section: Discussionmentioning

confidence: 99%

“…Studies conducted in Chinese populations with varying iodine status found that when iodine in the external environment increased (salt fortification and increased iodine in water supply), UIC increased while serum iodine remained more stable in comparison [ 25 , 45 ]. Another study conducted in Chinese adults found serum iodine was positively correlated with total T3 and T4 and free T4 concentrations [ 46 ], suggesting that serum iodine appears to most closely represent the bioavailable iodine for the thyroid gland, with 80–90% of total serum iodine incorporated into thyroid hormones [ 46 , 50 ]. While in overall agreement with previous studies, our study found significant increases in serum iodine only when iodine intake is excessive.…”

Section: Discussionmentioning

confidence: 99%

Reflection of Dietary Iodine in the 24 h Urinary Iodine Concentration, Serum Iodine and Thyroglobulin as Biomarkers of Iodine Status: A Pilot Study

et al. 2021

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Background: The iodine status of the US population is considered adequate, but subpopulations remain at risk for iodine deficiency and a biomarker of individual iodine status has yet to be determined. The purpose of this study was to determine whether a 3 day titration diet, providing known quantities of iodized salt, is reflected in 24 h urinary iodine concentration (UIC), serum iodine, and thyroglobulin (Tg). Methods: A total of 10 participants (31.3 ± 4.0 years, 76.1 ± 6.3 kg) completed three, 3 day iodine titration diets (minimal iodine, US RDA, (United States Recommended Daily Allowance), and 3× RDA). The 24 h UIC, serum iodine, and Tg were measured following each diet. The 24 h UIC and an iodine-specific food frequency questionnaire (FFQ) were completed at baseline. Results: UIC increased an average of 19.3 μg/L for every gram of iodized salt consumed and was different from minimal to RDA (p = 0.001) and RDA to 3× RDA diets (p = 0.04). Serum iodine was different from RDA to 3× RDA (p = 0.006) whereas Tg was not responsive to diet. Baseline UIC was associated with iodine intake from milk (r = 0.688, p = 0.028) and fish/seafood (r = 0.646, p = 0.043). Conclusion: These results suggest that 24 h UIC and serum iodine may be reflective of individual iodine status and may serve as biomarkers of iodine status.

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“…In addition, some subgroup analyses involved a small study population; hence, the lack of association of TPOAb status and preterm birth and miscarriages may be due to type 2 statistical error. Finally, no iodine intake measurements were taken for the study; however, there is universal salt iodination in China and the city of Beijing is an iodine-sufficient region [44].…”

Section: Discussionmentioning

confidence: 99%

Relationship between anti-thyroid peroxidase antibody positivity and pregnancy-related and fetal outcomes in Euthyroid women: a single-center cohort study

Yuan

Sun

et al. 2020

BMC Pregnancy Childbirth

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Background: Thyroid autoimmunity (TAI) and subclinical hypothyroidism (SCH) have been associated with poor pregnancy and fetal outcomes. However, whether euthyroid women with anti-thyroid peroxidase antibody (TPOAb) positivity have a higher risk of poor pregnancy and fetal outcomes is debatable. Therefore, this study aimed to investigate the association between TPOAb positivity and pregnancy-related and fetal outcomes in euthyroid women. Methods: In total, 938 pregnant women participated in this prospective cohort study. The euthyroid group included 837 pregnant women and the TPOAb-positive group included 101 euthyroid pregnant women. Serum TPOAb, thyroglobulin antibody (TGAb), thyroid-stimulating hormone (TSH), and free thyroxine (FT4) levels were assessed. Pregnancy and fetal outcomes included gestational diabetes mellitus, spontaneous abortion, premature rupture of membranes, hypertensive disorders of pregnancy, preterm birth, fetal distress, low birth weight, fetal macrosomia, and small for gestational age infant. Results: Logistic regression analysis showed TPOAb positivity was not associated with an increased risk of poor pregnancy or fetal outcomes in euthyroid women. However, TPOAb-positive euthyroid women pregnant with a female fetus were independently associated with preterm births (OR: 4.511, 95% CI: 1.075-18.926) after adjustment for potential confounding factors.

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Establishing reference intervals for urine and serum iodine levels: A nationwide multicenter study of a euthyroid Chinese population

Cited by 19 publications

References 23 publications

The Prevalence and Risk Factors Associated with Iodine Deficiency in Canadian Adults

The Prevalence and Risk Factors Associated with Iodine Deficiency in Canadian Adults

Reflection of Dietary Iodine in the 24 h Urinary Iodine Concentration, Serum Iodine and Thyroglobulin as Biomarkers of Iodine Status: A Pilot Study

Relationship between anti-thyroid peroxidase antibody positivity and pregnancy-related and fetal outcomes in Euthyroid women: a single-center cohort study

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