Urinary Iodine Concentration as an Indicator of Iodine Status and its Correlation with the Thyroid Hormones and Hemoglobin Levels in First Trimester Pregnant Women - An Exploratory Study

During pregnancy, the daily requirement of iodine increases making those most at-risk population for iodine deficiency disorders. The available confined data shows that pregnant women are iodine deficient even in iodine sufficient regions with this background the objectives of the current study were to assess the urinary iodine concentration (UIC) and evaluate the relationship between the levels of hemoglobin, UIC, and thyroid status in first-trimester pregnant women. A cross-sectional hospital-based study with a total sample size of n=110 pregnant women at the13th week of gestation in the Mysuru district was selected. The UIC, anthropometric measurements, iodine intake, and selected biochemical parameters (TSH, FT3, FT4, and Hb) were assessed. The data was analysed using SPSS (v 16.0). Spearman’s rank correlation test was used to analyse correlations. The Mann- Whitney U test was used to compare differences between groups. ANOVA was used to study the comparison of pregnancy complications with UIC and hemoglobin. The median UIC (mUIC) was 194.2 µg/L and Hb was 10.5 g/dL. Even though the mUIC was normal, around 38.2% had insufficient UIC. Significant inverse relationship between UIC and TSH (r = -0.487, p<0.001), Hb and TSH (r = -0.355, p < 0.001), and between TSH and iodine intake (r=-0.476, p<0.001) were observed. It was interesting to observe that those with insufficient UIC were found to have mild anaemia and low FT4 levels and those with excess UIC had lower TSH levels. The pregnant women in the present study were found to have the normal median urinary iodine concentration and were mildly anaemic. Increased attention among pregnant women should be focused on iodine status along with iron status and thyroid functions. Larger comparative studies need to be performed to study the impact of altered iodine status on neonatal outcomes.

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The impact of iodised salt or iodine supplements on iodine status during pregnancy, lactation and infancy

Public Health Nutrition ◽

10.1017/s1368980007360965 ◽

2007 ◽

Vol 10 (12A) ◽

pp. 1584-1595 ◽

Cited By ~ 50

Author(s):

Michael B Zimmermann

Keyword(s):

Pregnant Women ◽

Urinary Iodine ◽

Iodine Concentration ◽

Iodine Intake ◽

Urinary Iodine Concentration ◽

Life Stages ◽

Lactating Women ◽

Iodine Status ◽

Iodised Salt ◽

The Impact

AbstractObjectives:Monitoring of iodine status during pregnancy, lactation and infancy is difficult as there are no established reference criteria for urinary iodine concentration (UI) for these groups; so it is uncertain whether iodized salt programs meet the needs of these life stages.Design and Subjects:The method used in this paper was: 1) to estimate the median UI concentration that reflects adequate iodine intake during these life stages; and 2) to use these estimates in a review of the literature to assess whether salt iodisation can control iodine deficiency in pregnant and lactating women, and their infants.Results:For pregnancy, recommended mean daily iodine intakes of 220-250 μg were estimated to correspond to a median UI concentration of about 150 μg l− 1, and larger surveys from the iodine sufficient countries have reported a median UI in pregnant women ≥ 140 μg l− 1. Iodine supplementation in pregnant women who are mild-to-moderately iodine deficient is beneficial, but there is no clear affect on maternal or newborn thyroid hormone levels. In countries where the iodine intake is sufficient, most mothers have median breast milk iodine concentration (BMIC) greater than the concentration (100-120 μg l− 1) required to meet an infant's needs. The median UI concentration during infancy that indicates optimal iodine nutrition is estimated to be ≥ 100 μg l− 1. In iodine-sufficient countries, the median UI concentration in infants ranges from 90-170 μg l− 1, suggesting adequate iodine intake in infancy.Conclusions:These findings suggest pregnant and lactating women and their infants in countries with successful sustained iodised salt programs have adequate iodine status.

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Dried Blood Spot Thyroglobulin as a Biomarker of Iodine Status in Pregnant Women

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2016-2829 ◽

2016 ◽

Vol 102 (1) ◽

pp. 23-32 ◽

Cited By ~ 30

Author(s):

Sara Stinca ◽

Maria Andersson ◽

Sandra Weibel ◽

Isabelle Herter-Aeberli ◽

Ralph Fingerhut ◽

...

Keyword(s):

Pregnant Women ◽

Reference Range ◽

Urinary Iodine ◽

Iodine Intake ◽

Dried Blood Spot ◽

Urinary Iodine Concentration ◽

Iodine Nutrition ◽

Cross Sectional ◽

Iodine Status ◽

Blood Spot

Abstract Context: Thyroglobulin (Tg) could be a sensitive biomarker of iodine nutrition in pregnant women (PW). A dried blood spot (DBS) assay would simplify collection and transport in field studies. Objectives: Our aims were to (1) establish and test a reference range for DBS-Tg in PW; (2) determine whether co-measurement of Tg antibodies (Abs) is necessary to define population iodine status. Design, Setting, and Participants: Standardized cross-sectional studies of 3870 PW from 11 countries. For the DBS-Tg reference range, we included TgAb-negative PW (n = 599) from 3 countries with sufficient iodine intake. Main Outcome Measures: We measured the urinary iodine concentration and DBS thyroid-stimulating hormone, total thyroxin, Tg, and TgAb. Results: In the reference population, the median DBS-Tg was 9.2 μg/L (95% confidence interval, 8.7 to 9.8 μg/L) and was not significantly different among trimesters. The reference range was 0.3 to 43.5 μg/L. Over a range of iodine intake, the Tg concentrations were U-shaped. Within countries, the median DBS-Tg and the presence of elevated DBS-Tg did not differ significantly between all PW and PW who were TgAb-negative. Conclusions: A median DBS-Tg of ∼10 μg/L with <3% of values ≥44 μg/L indicated population iodine sufficiency. Concurrent measurement of TgAb did not appear necessary to assess the population iodine status.

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Indicators of Iodine Status in Pregnancy and Postpartum in a Group of Pregnant Women from Perimarine Area of Romania

ARS Medica Tomitana ◽

10.2478/arsm-2020-0013 ◽

2020 ◽

Vol 26 (2) ◽

pp. 63-69

Author(s):

Scrinic Olesea ◽

Delia Corina Elena ◽

Toma Geanina Mirela ◽

Circo Eduard

Keyword(s):

Pregnant Women ◽

Iodine Deficiency ◽

Urinary Iodine ◽

Iodine Concentration ◽

Iodine Intake ◽

Iodized Salt ◽

Urinary Iodine Concentration ◽

Urinary Creatinine ◽

Iodine Status ◽

In Pregnancy

Abstract Objective: Assessment of iodine nutritional status in pregnant women in the perimarine area of Romania, a region without iodine deficiency. Adequate iodine intake is the main source for normal thyroid function, ensuring the need for maternal thyroid hormones during pregnancy, but also for the development and growth of children in the fetal and postpartum period. Material and method: Prospective study performed on 74 pregnant women in the first 2 trimesters of pregnancy, originating from the perimarin area. The following indicators of iodine status were analyzed: urinary iodine concentration (UIC), the ratio between urinary iodine concentration and urinary creatinine (UIC/UCr), the prevalence of maternal goiter and the value of neonatal TSH (thyroid stimulating hormone). Results: The mean gestational age was 11 weeks. The ways of iodine intake are: iodized salt - 59.4%, iodized salt and iodine supplements- 23%, only iodine supplements -10.8% and 6.8% consume only non-iodized salt. The median of UIC was 133.03 mcg/l considered insufficient iodine intake (normal in pregnancy UIC >150 mcg/l), but the adjustment of UIC to urinary creatinine reveals a median of 152.83 mcg/g, a value that reflects an adequate iodine intake. The prevalence of goiter was 25.6% characteristic for a moderate iodine deficiency. The prevalence of neonatal TSH >5 mIU/L was registered in 18.8% characteristic of mild iodine deficiency. Conclusions: Monitoring of the iodine nutritional status is recommended for the prevention of disorders due to iodine deficiency under the conditions of universal salt iodization. Perimarine areas considered sufficient in iodine may show variations in iodine status in subpopulations under certain physiological conditions, such as pregnancy. An indicator of iodine status of the population is UIC, but the UIC/UCr ratio may be a more optimal indicator for pregnant women, to avoid possible overestimated results of iodine deficiency in pregnancy.

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Current iodine status in Japan: A cross-sectional nationwide survey of schoolchildren, 2014–2019

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/clinem/dgab919 ◽

2021 ◽

Author(s):

Yozen Fuse ◽

Yoshiya Ito ◽

Yoshimasa Shishiba ◽

Minoru Irie

Keyword(s):

Urinary Iodine ◽

Nationwide Survey ◽

Iodine Concentration ◽

Iodine Intake ◽

Urinary Iodine Excretion ◽

Urinary Iodine Concentration ◽

Cross Sectional ◽

Iodine Status ◽

Iodine Excretion ◽

Cr Concentration

Abstract Context Japan has been regarded as a long-standing iodine sufficient country without iodine fortification; however, data on nationwide iodine status is lacking. Objective This study aimed to characterize the iodine status in Japan. Methods From 2014 through 2019 a nationwide school-based survey was conducted across all districts in Japan. Urinary iodine concentration (UIC), creatinine (Cr) concentration and anthropometry were assessed in healthy school-aged children (SAC) aged 6 to 12 years. Their iodine status is regarded as generally representative of the nation's iodine status. Results A total of 32,025 children participated. The overall median UIC was 269 μg/L which was within the WHO’s adequacy range. There was a regional difference in UIC values within 14 regions, and the lowest and highest median UIC were found in Tanegashima Island (209 μg/L) and Nakashibetsu, Hokkaido (1,071 μg/L), respectively. The median UIC ≥ 300 μg/L was observed in 12 out of 46 regions. By using estimated 24-h urinary iodine excretion (UIE), the prevalence of SAC exceeding the upper tolerable limit of iodine for Japanese children was from 5.2 to 13.7%. The UIC values did not change with age, BSA and BMI percentile, while the Cr concentration simultaneously increased suggesting the effect of urinary creatinine on UI/Cr and estimated 24-h UIE values. Conclusions The iodine intake of Japanese people is adequate, but in some areas it is excessive. The incidence and prevalence of thyroid disorders associated with iodine intake should be obtained especially in the areas where high amounts of iodine are consumed.

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Mild to Moderate Iodine Deficiency and Inadequate Iodine Intake in Lactating Women in the Inland Area of Norway

Nutrients ◽

10.3390/nu12030630 ◽

2020 ◽

Vol 12 (3) ◽

pp. 630 ◽

Cited By ~ 1

Author(s):

Synne Groufh-Jacobsen ◽

Lise Mette Mosand ◽

Ingvild Oma ◽

Kjersti Sletten Bakken ◽

Beate Stokke Solvik ◽

...

Keyword(s):

Human Milk ◽

Infant Health ◽

Urinary Iodine ◽

Iodine Concentration ◽

Iodine Intake ◽

Public Health Care ◽

Urinary Iodine Concentration ◽

Cross Sectional ◽

Lactating Women ◽

Iodine Status

Breastfed infants are dependent on an adequate supply of iodine in human milk for the production of thyroid hormones, necessary for development of the brain. Despite the importance of iodine for infant health, data on Norwegian lactating women are scarce. We measured iodine intake and evaluated iodine status and iodine knowledge among lactating women. From October to December 2018, 133 mother–infant pairs were recruited in a cross-sectional study through two public health care centers in Lillehammer and Gjøvik. Each of the women provided two human milk specimens, which were pooled, and one urine sample for analysis of iodine concentration. We used 24-h dietary recall and food frequency questionnaire (FFQ) to estimate short-term and habitual iodine intake from food and supplements. The median (P25, P75) human milk iodine concentration (HMIC) was 71 (45, 127) µg/L—of which, 66% had HMIC <100 µg/L. The median (P25, P75) urinary iodine concentration (UIC) was 80 µg/L (52, 141). The mean (± SD) 24-h iodine intake and habitual intake was 78 ± 79 µg/day and 75 ± 73 µg/day, respectively. In conclusion, this study confirms inadequate iodine intake and insufficient iodine status among lactating women in the inland area of Norway and medium knowledge awareness about iodine.

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Iodine deficiency among Belgian pregnant women not fully corrected by iodine-containing multivitamins: a national cross-sectional survey

British Journal Of Nutrition ◽

10.1017/s0007114512004473 ◽

2012 ◽

Vol 109 (12) ◽

pp. 2276-2284 ◽

Cited By ~ 32

Author(s):

Stefanie Vandevijvere ◽

Sihame Amsalkhir ◽

Ahmed Bensouda Mourri ◽

Herman Van Oyen ◽

Rodrigo Moreno-Reyes

Keyword(s):

Pregnant Women ◽

Iodine Deficiency ◽

Urinary Iodine ◽

Iodine Intake ◽

Urinary Iodine Concentration ◽

Childbearing Age ◽

Third Trimester ◽

Cross Sectional Survey ◽

Cross Sectional ◽

Iodine Status

Low iodine intake during pregnancy may cause thyroid dysfunction in pregnant women and their newborn. In the present study, iodine status among a nation-wide representative sample of Belgian pregnant women in the first and third trimester of pregnancy was determined, and determinants of iodine status were assessed 1 year after the introduction of bread fortified with iodised salt. The women were selected according to a multistage proportionate-to-size sampling design. Urine samples were collected and a general questionnaire was completed face to face with the study nurse. The median urinary iodine concentration (UIC) among pregnant women (n1311) was 124·1 μg/l and 122·6 μg/g creatinine when corrected for urinary creatinine. The median UIC in the first trimester (118·3 μg/l) was significantly lower than that in the third trimester (131·0 μg/l) but significantly higher than among non-pregnant women (84·8 μg/l). Iodine-containing supplement intake was reported by 60·8 % of the women and 57·4 % of the women took this supplement daily. The risk of iodine deficiency was significantly higher in younger women, in women not taking iodine-containing supplements, with low consumption of milk and dairy drinks and during autumn. Women with a higher BMI had a higher risk of iodine deficiency but the risk was lower in women who reported alcohol consumption. The median UIC during pregnancy indicates iodine deficiency in Belgium and some women are at a higher risk of deficiency. The current low iodine intake in women of childbearing age precludes the correction of iodine deficiency in pregnant women supplemented with multivitamins containing 150 μg iodine as recommended.

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Factors associated with inadequate urinary iodine concentration among pregnant women in Mbeya region Tanzania.

F1000Research ◽

10.12688/f1000research.55269.1 ◽

2021 ◽

Vol 10 ◽

pp. 858

Author(s):

Tedson Lukindo ◽

Ray Masumo ◽

Adam Hancy ◽

Sauli E. John ◽

Heavenlight A. Paulo ◽

...

Keyword(s):

Pregnant Women ◽

Urinary Iodine ◽

Public Health Problem ◽

Iodine Concentration ◽

Iodine Intake ◽

Urinary Iodine Concentration ◽

Iodine Status ◽

Excess Iodine ◽

Increased Risk ◽

Recommended Level

Background: Deficient and excess iodine intake during pregnancy can lead to serious health problems. In Tanzania, information available on iodine status during pregnancy is minimal. The aim of this study was to assess the iodine status and its association with sociodemographic factors in pregnant women in the Mbeya region, Tanzania. Method: A cross sectional survey involving 420 pregnant women (n=420) aged between 15-49 years registered in antenatal care clinics was conducted. Data were collected via interviews and laboratory analysis of urinary iodine concentration (UIC). Results: Median UIC was 279.4μg/L (+/-26.1) to 1915μg/L. Insufficient iodine intake (UIC below 150μg/L) was observed in 17.14% of participants, sufficient intake in 24.29% and 58.57% had intakes above the recommended level (>250μg/L). Rungwe district council (DC) had the highest proportion of patients (27.9%) with low iodine levels, while Chunya and Mbarali DCs had the greatest proportion of those with UIC’s, over the WHO recommended level. Fish consumption and education status were associated with increased risk of insufficient iodine while individuals in Mbalali DC aged between 35-49 years were associated with increased risk of UIC above recommended level. Conclusion: Both deficient and excess iodine intake remains a public health problem, especially in pregnant women in Tanzania. Therefore, educational programs on iodine intake are needed to ensure this population has an appropriate iodine intake to prevent any health risks to the mother and the unborn child.

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Trimester-Specific Thyroid Function in Pregnant Women with Different Iodine Statuses

Annals of Nutrition and Metabolism ◽

10.1159/000506276 ◽

2020 ◽

Vol 76 (3) ◽

pp. 165-174

Author(s):

Wenxing Guo ◽

Wei Wang ◽

Ya Jin ◽

Wen Chen ◽

Lu Chen ◽

...

Keyword(s):

Pregnant Women ◽

Thyroid Function ◽

Urinary Iodine ◽

Thyroid Volume ◽

First Trimester ◽

Urinary Iodine Concentration ◽

Free Triiodothyronine ◽

Cross Sectional ◽

Iodine Status ◽

Spot Urine

Objectives: To explore trimester-specific thyroid function changes under different iodine statuses throughout pregnancy. Methods: A cross-sectional study was conducted to assess the pregnancy iodine status, and 2,378 healthy pregnant women covering all 3 trimesters were recruited. Urinary iodine concentration (UIC) was measured by collecting spot urine samples. Blood samples were collected to evaluate thyroid function. Thyroid B-ultrasonography was conducted to measure the thyroid volume (Tvol). Results: The median UIC was 168 μg/L (111–263 μg/L). The UIC, free triiodothyronine (FT3), and free thyroxine (FT4) were significantly decreased as the pregnancy progressed (p < 0.001, p for trend <0.001), while Tvol increased (p < 0.001, p for trend <0.001). Thyrotropin (TSH) was significantly different between the 3 trimesters and showed an upward trend (p < 0.001), but the p for trend was not significant (p for trend = 0.88). After stratification by UIC, there were no significant differences in serum TSH, FT4, or FT3 level between UIC groups. Tvol was significantly higher in the UIC ≥500 μg/L group in the first trimester (β: 2.41, 95% CI: 1.09–3.72, p <0.001), as well as in the 250 ≤ UIC < 500 μg/L group (β: 1.65, 95% CI: 0.61–2.70, p < 0.001) and UIC ≥500 μg/L group (β: 3.35, 95% CI: 1.96–4.74, p < 0.001) in the third trimester. Conclusions: No difference was observed in TSH, FT3, or FT4 among the different iodine status groups throughout pregnancy. Tvol increased as the pregnancy progressed, and it was especially higher in the UIC ≥500 μg/L group in the first and third trimesters.

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Iodine Deficiency in Latvia: Current Status and Need for National Recommendations

Proceedings of the Latvian Academy of Sciences Section B Natural Exact and Applied Sciences ◽

10.1515/prolas-2017-0071 ◽

2017 ◽

Vol 71 (6) ◽

pp. 401-407

Author(s):

Ilze Konrāde ◽

Ieva Kalere ◽

Ieva Strēle ◽

Marina Makrecka-Kūka ◽

Vija Veisa ◽

...

Keyword(s):

Pregnant Women ◽

Iodine Deficiency ◽

Urinary Iodine ◽

Iodine Concentration ◽

Iodine Intake ◽

Medical Decision ◽

Current Status ◽

Urinary Iodine Concentration ◽

Childbearing Age ◽

Cross Sectional

Abstract In the absence of a mandatory salt iodisation programme, two nationwide cross-sectional cluster surveys revealed persisting iodine deficiency among Latvian schoolchildren during the spring season and a noteworthy iodine deficiency in pregnant women in Latvia; these deficiencies warrant intervention. The consequences of mild-to-moderate iodine deficiency during pregnancy and lactation can adversely affect foetal brain development. Data from a Latvian population survey revealed the consumption of approximately 100 μg of iodine per day through foods and iodised salt. Therefore, strategies to increase the consumption of iodine-containing products should be implemented, particularly for children. In addition, to meet the increased iodine requirement during pregnancy, pregnant women should take daily supplements containing 150 μg iodine from the earliest time possible. All women of childbearing age should be advised to increase their dietary iodine intake by using iodised table salt and iodine-rich products: seafood, milk and milk products. For women with pre-existing thyroid pathologies, the medical decision should be considered on a case-by-case basis. Urinary iodine concentration monitoring among schoolchildren and pregnant women and neonatal thyrotropin registry analysis every five years would be an appropriate strategy for maintaining iodine intake within the interval that prevents iodine deficiency disorders.

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Is it Necessary to Recommend Iodine Supplement to Pregnant Women Living in Areas with Adequate Iodine Intake?

Shiraz E-Medical Journal ◽

10.5812/semj.98627 ◽

2020 ◽

Vol In Press (In Press) ◽

Author(s):

Mahmood Sovid ◽

Maryam Bahmani ◽

Alamtaj Aamsami

Keyword(s):

Pregnant Women ◽

Significant Proportion ◽

Urinary Iodine ◽

Iodine Concentration ◽

Iodine Intake ◽

Thyroid Stimulating Hormone ◽

Urinary Iodine Concentration ◽

Cross Sectional ◽

Group 2 ◽

Group 1

Background: Iodine need is increased during pregnancy and its deficiency can lead to complications in mother and fetus. The latest international guidelines have recommended a higher intake of iodine. Iran has implemented a national salt iodization program since 25 years ago, and the general population is iodine-sufficient. However, recent studies have shown that a significant proportion of pregnant women have urinary iodine concentration (UIC) below the recommended range of 150 - 250 µg/L. Based on the results of these studies, iodine supplement during pregnancy is widely used, but this practice is controversial. Objectives: The aim of this study was to evaluate the necessity for iodine supplementation in pregnant women living in Shiraz, an iodine-replete area. Methods: In this cross-sectional case-control study, UIC and thyroid-stimulating hormone of 174 pregnant women taking 150 µg/day iodine (group 1) were compared with 124 pregnant women not taking the supplement (group 2). The proportion of women with UIC below the recommended level in each group was also determined. UIC of the women in different trimesters in each group was also investigated and compared. Results: Mean UIC in groups 1 and 2 was 175.71 ± 56.43 µg/Land 122.5 ± 44.37 µg/L and this difference was significant (P = 0.006). Also, 56% of women in group 2 and 24 % in group 1 had UIC below the recommended value (P < 0.01). Mean UIC in both groups decreased with advancing gestational age. In group 1, mean UIC remained in the recommended range, whereas in group 2, it decreased to less than 100 µg/L. Conclusions: In areas covered by the national salt iodine implementation program, it is necessary to recommend iodine supplement to pregnant women to prevent iodine insufficiency.

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