Iodine Nutrition Of Pregnant Women Research Articles

Salivary iodine concentration in pregnant women and its association with iodine status and thyroid function.

There have been no reports on the application of salivary iodine concentration (SIC) in evaluating iodine nutrition in pregnant women. This study aimed to clarify the relationship between SIC and indicators of iodine nutritional status and thyroid function during pregnancy, to investigate whether salivary iodine can be applied to the evaluation of iodine nutritional status in pregnant women, and to provide a reference basis for establishing a normal range of salivary iodine values during pregnancy. Pregnant women were enrolled in the Department of Obstetrics, the people's hospital of Yuncheng Country, Shandong Province, from July 2021 to December 2022, using random cluster sampling. Saliva, urine, and blood samples were collected from pregnant women to assess iodine nutritional status, and venous blood was collected to determine thyroid function. A total of 609 pregnant women were included in this study. The median spot urinary iodine concentration (SUIC) was 261μg/L. The median SIC was 297μg/L. SIC was positively correlated with SUIC (r = 0.46, P < 0.0001), 24-h UIC (r = 0.30, P < 0.0001), 24-h urinary iodine excretion (24-h UIE) (r = 0.41, P < 0.0001), and estimated iodine intake (EII) (r = 0.52, P < 0.0001). After adjusting for confounders, there was a weak correlation between SIC and serum total iodine and serum non-protein-bound iodine (P = 0.02, P = 0.04, respectively). Pregnant women with a SIC < 176μg/L had a higher risk of insufficient iodine status (OR = 2.07, 95% CI 1.35-3.19) and thyroid dysfunction (OR = 2.71, 95% CI 1.18-6.21) compared to those with higher SIC. Those having SIC > 529μg/L were more likely to have excessive iodine status (OR = 2.82, 95% CI 1.81-4.38) and thyroid dysfunction (OR = 3.04, 95% CI 1.36-6.78) than those with lower SIC values. SIC is associated with urinary iodine concentration and thyroid function in pregnant women. SIC < 176μg/L was associated with an increased risk for iodine deficiency and hypothyroxinemia, while SIC > 529μg/L was related to excess and thyrotoxicosis. SIC can be used as a reference indicator for evaluating the iodine nutrition status of pregnant women, but it needs further investigation and verification. NCT04492657(Aug 9, 2022).

Thyroglobulin as a Sensitive Biomarker of Iodine Status in Mildly and Moderately Iodine-Deficient Pregnant Women

Pregnant women are more susceptible to iodine deficiency. However, there are limitations in existing indicators for the evaluation of iodine nutrition in pregnant women. The study aimed to explore whether thyroglobulin (Tg) can be used as a more sensitive biomarker for pregnant women with mild and moderate iodine deficiency. A repeated-measure study was conducted among 1332 pregnant women in Zhejiang Province, China. Serum and urine specimens were collected at a mean of 10, 17, and 32 weeks of pregnancy, respectively; thyroid-stimulating hormone (TSH), Tg, and urinary iodine concentrations were measured. Linear mixed effects models were used to determine the associations between interaction of iodine concentrations and increasing gestation week and TSH and Tg, where participants were divided by urinary iodine concentration (UIC). The median Tg concentration was 11.56, 11.45, and 12.43 μg/L in the first, second, and third trimesters, respectively. After controlling the covariates, the interaction effects between the iodine status and gestation week were significant for both TSH and Tg (p = 0.038 and p = 0.007, respectively). TSH increased with the week of gestation in both iodine concentration groups. Tg increased with advancing pregnancy in the iodine-deficient group whereas it did not in the iodine-sufficient group. There was no significant variation in TSH at each trimester, and Tg was higher in the iodine-deficient group than in the iodine-sufficient group. Tg may be a more sensitive iodine status biomarker than TSH for pregnant women with mild-to-moderate iodine insufficiency.

Adverse Effects on the Thyroid of Chinese Pregnant Women Exposed to Long-Term Iodine Excess: Optimal and Safe Tolerable Upper Intake Levels of Iodine

Ensuring optimal iodine nutrition in pregnant women is a global public health concern. However, there is no direct data on safe tolerable upper intake levels (ULs) for pregnant women. A cross-sectional study was performed to determine the ULs of pregnant women. A total of 744 pregnant women were enrolled in this study. The median (IQR) urinary iodine concentration (UIC) in pregnant women was 150.2 (87.6, 268.0) μg/L, and the urinary iodine excretion (UIE) over 24 h was 204.2 (116.0, 387.0) μg/day. Compared with those with a UIE figure of between 150-250 μg/day, the reference group, the prevalence of thyroid dysfunction was 5.7 times higher (95%CI: 1.7, 19.2) in pregnant women with a UIE figure of between 450-550 μg/day, and 3.9 times higher (95%CI: 1.5, 10.3) in pregnant women with a UIE figure of ≥550 μg/day. Compared with an estimated iodine intake (EII) of between 100-200 μg/day, the reference group, the prevalence of thyroid dysfunction was 4.3 times higher (95%CI: 1.3, 14.4) in pregnant women with a UIE figure of between 500-600 μg/day, and 3.6 times higher (95%CI: 1.5, 8.9) in pregnant women with UIE of ≥600 μg/day. In general, our cross-sectional study found that excessive iodine intake during pregnancy appears to directly increase the risk of thyroid dysfunction. Avoiding chronic iodine intakes of 500 μg/day or higher or having a UIE figure of ≥450 μg/day is recommended for pregnant women in China.

Iodine status, household salt iodine content, knowledge and practice assessment among pregnant women in Butajira, South Central Ethiopia.

Iodine is one of the crucial micronutrients needed by the human body, and is vitally important during pregnancy. This study aimed to determine the relationship between the iodine status of pregnant women and their knowledge, and practices regarding iodized salt. All participants were enrolled in the Butajira nutrition, mental health and pregnancy (BUNMAP) cohort, Butajira, Ethiopia in February-May, 2019. In this cross-sectional study, 152 pregnant women without hypertension or known thyroid disease before or during pregnancy were randomly selected from the BUNMAP mother to child cohort (n = 832). Spot urine samples were collected to estimate the level of urinary iodine concentration (UIC). Salt samples were also collected from their homes. The Sandall-Kolthoff (S-K) method was used to measure the level of iodine in the urine samples, and iodometric titration was used to measure the level of iodine in the salt. Data was entered and cleaned using Epi-info version 3.5.3 and then exported to SPSS version 20 for further analysis. Multivariate logistic regression analysis was performed to identify associations in the collected data. The WHO recommended level of iodine for populations of pregnant women is 150-249 F06Dg/L. The median UIC among pregnant women in this study was 151.2 μg/L [interquartile range (IQR) = 85.5-236.2 F06Dg/L], at the low end of this range. About half (49.65%) of the participants were likely to be iodine deficient. There was a significant association between having a formal job (AOR = 2.56; CI = 1.11-5.96) and iodine sufficiency. Based on a cutoff of >15 ppm (mg/kg), 91.7% (95% CI: 87.2-96.2) of the salts collected from the household had adequate iodine content. The median iodine level of the collected salt samples was 34.9 mg/kg (ppm) (IQR = 24.2-44.6 mg/kg). The UNICEF 2018 guidelines for adequate iodine nutrition in pregnant women include both a recommended median range of 150-249 μg/L, and an upper limit of 20% on the fraction of the population with UIC below 50 μg/L. Because our study population's median level is 151.2 μg/L and the percentage of pregnant women with urinary iodine concentration of less than 50 μg/L is 9.7% (14/145), the women received adequate iodine nutrition. The availability of adequately iodized salt in households is more than 90%, as recommended by WHO. In light of previous iodine deficiency in this region of Ethiopia, the salt iodization program promotes the health of babies and mothers.

Iodine nutrition status and thyroid autoimmunity during pregnancy: a cross-sectional study of 4635 pregnant women

BackgroundPregnant women in Shanghai have long been at risk for mild iodine deficiency. Because thyroid autoimmunity in pregnant women can lead to premature birth and miscarriage as well as neurodevelopmental deficits in the fetus, the aim of this study was to explore the association of iodine nutrition status with thyroid antibodies during pregnancy.MethodsA pregnancy-birth cohort was conducted including 4635 pregnant women in Shanghai, China. The eligible participants underwent a face-to-face interview and completed questionnaire surveys to collect baseline information and diet intake. Spot urine samples were collected to test urine iodine. Thyroid antibodies including thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb) and thyrotrophic antibodies (TRAb) were tested. Single-factor analysis and logistic regression were used to evaluate the association between iodine status and thyroid autoimmunity during pregnancy.ResultsThe median urinary iodine excretion level in the sample was 138.14 μg/L (interquartile range [IQR] 80.90–219.00 μg/L). Among all the subjects, 25.9% consumed non-iodized salt, 54.5% had iodine deficiency, and 31.0% had thyroid autoimmunity. The proportion of patients with iodine deficiency was significantly higher among those who consumed non-iodized salt (36.9% vs. 33.1%; p = 0.04). After adjusting for age, educational status, former smoker status, former drinker status, first pregnancy, and previous thyroid disease, non-iodized salt (odds ratio [OR] = 1.394 [confidence interval, CI, 1.165–1.562]; p = 0.003), iodine-rich food (OR = 0.681 [CI 0.585–0.793]; p = 0.003), iodized nutritional supplements (OR = 0.427 [CI 0.347–0.526]; p = 0.003), were found to be individually associated with thyroid autoimmunity in all participants. The results of the multivariable restricted cubic spline regression analysis showed a non-linear relationship between the continuous change in iodine intake and thyroid autoimmunity (p = 0.019). Participants with iodine deficiency (urinary iodine concentration, UIC,< 100 μg/L) had an increased risk of testing positive for thyroid antibodies (TPOAb/TgAb/TRAb[+]; OR = 1.324 [CI 1.125–1.559]; p < 0.001). Moreover, this associated existed even after removing participants with previous thyroid disease.ConclusionInadequate iodine nutrition in pregnant women is an independent risk factor for thyroid autoimmunity in Shanghai. It’s important to maintain the adequate iodine status in pregnant women.

Iodine Nutrition Status and Thyroid Autoimmunity During Pregnancy: A Cross-Sectional Study of 4635 Pregnant Women

BackgroundPregnant women in Shanghai have long been at risk for mild iodine deficiency. Because thyroid autoimmunity in pregnant women can lead to premature birth and miscarriage as well as neurodevelopmental deficits in the fetus, the aim of this study was to explore the association of iodine nutrition status with thyroid antibodies during pregnancy.MethodsA pregnancy-birth cohort was conducted including 4635 pregnant women in Shanghai, China. The eligible participants underwent a face-to-face interview and completed questionnaire surveys to collected baseline information and diet intake. Spot urine samples were collected to test urine iodine. Thyroid antibodies including thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb) and thyrotrophic antibodies (TRAb) were tested. Single-factor analysis and logistic regression were used to evaluate the association between iodine status and thyroid autoimmunity during pregnancy.FindingsThe median urinary iodine excretion level in the sample was 138·14 µg/L (interquartile range [IQR] 80·90-219·00 µg/L). The proportion of patients with iodine deficiency was significantly higher among those who consumed non-iodized salt (36·9% vs. 33·1%; p = 0·04). After adjusting for age, educational status, former smoker status, former drinker status, first pregnancy, and previous thyroid disease, non-iodized salt (odds ratio [OR] = 1·394 [confidence interval, CI, 1·165-1·562]; p = 0·003), iodine-rich food (OR = 0·681 [CI 0·585-0·793]; p = 0·003), iodized nutritional supplements (OR = 0·427 [CI 0·347-0·526]; p = 0·003), were found to be individually associated with thyroid autoimmunity in all participants. The results of the multivariable restricted cubic spline regression analysis showed a non-linear relationship between the continuous change in iodine intake and thyroid autoimmunity (p = 0·019). Participants with iodine deficiency (urinary iodine concentration, <100 µg/L) had an increased risk of testing positive for thyroid antibodies (TPOAb/TgAb/TRAb[+]; OR = 1·324 [CI 1·125-1·559]; p < 0·001). Moreover, this associated existed even after removing participants with previous thyroid disease.InterpretationInadequate iodine nutrition in pregnant women is an independent risk factor for thyroid autoimmunity in Shanghai, where the overall nutrition status is good. Funding: This study was supported by the young fund of Shanghai municipal health commission (20194Y0443), food nutrition research and education fund of Danone nutrition center (DIC2019-03), excellent young talents of health system in Shanghai (No. 2017YQ043) and top young talents in Shanghai (No. 2020-8). Declaration of Interest: None to declare. Ethical Approval: The study was approved by the Ethics Committee of Shanghai Center for Disease Control and Prevention (SCDC) and was performed in accordance with the Declaration of Helsinki. Before data collection, written informed consent was obtained from all participants.

Iodine Nutrition and Thyroid Function in Pregnant Women Exposed to Different Iodine Sources.

Pregnant women are more vulnerable to iodine deficiency and iodine excess. The study aimed to assess the changes in iodine nutrition and thyroid function of pregnant women exposed to different iodine sources resulting in various iodine intakes during pregnancy. From 2016 to 2017, 2004 healthy pregnant women aged 20-35years from Shandong and Tianjin, China, were enrolled. Urinary iodine concentration (UIC), drinking water iodine content (WIC), thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroid hormone (FT4), thyroglobulin (Tg), serum thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb) were measured. Pregnant women in both Shandong and Tianjin were iodine sufficient, but the median UIC in pregnant women was significantly higher in Shandong (244μg/L) than thatin Tianjin (159μg/L). No differences were found in UIC over the course of gestation in Shandong. In Tianjin, the UIC decreased during 13-24weeks and stabilized thereafter. Compared with Tianjin, TSH levels were higher and FT3 and FT4 levels were lower in Shandong. Both FT3 and FT4 significantly decreased during pregnancy in Shandong and Tianjin. TSH and Tg increased over the course of gestation in both Shandong and Tianjin. The iodine status of pregnant women in Tianjin and Shandong were sufficient, but different changing patterns in UIC and thyroid function during pregnancy were presented. More attention should be focused on iodine nutrition of pregnant women, even in iodine-sufficient areas.

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

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. 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. 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. We measured the urinary iodine concentration and DBS thyroid-stimulating hormone, total thyroxin, Tg, and TgAb. 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. 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.

Inadequate iodine nutrition of pregnant women in an area of iodine sufficiency.

I. R. Iran has been considered iodine replete since 2000, but iodine nutrition of vulnerable subjects is not clear. The main goal of this study was assessment of iodine nutrition and thyroid function in pregnant Iranian women. A total of 1072 pregnant women from ten provinces in the different parts of the country were recruited from November to March 2014. Median urinary iodine concentration (UIC) as the measure of iodine status and serum free T4 (FT4), thyrotropin (TSH), thyroglobulin (Tg), anti-thyroglobulin and anti-thyroid peroxidase antibodies (TgAb and TPOAb) were measured. Mean±SD age of the cohort was 27.0±7.2years and gestational age was 20.7±10.0weeks. The median UIC for pregnant women was 87.3μg/L, being 92.1, 86.0 and 76.8μg/L, in three trimesters of pregnancy, respectively. Median UIC of <100, 100-149, 150-249, 250-499 and ≥500μg/L was found in 58.4, 19.8, 16.2, 5.13 and 0.46% of subjects, respectively. Median (IQR) values in the first, second, and third trimesters were 1.7 (0.9-2.8), 2.1 (1.5-2.9), and 2.1 (1.4-2.8) mIU/L for TSH, and 16.4 (12.21-21.13), 14.34 (12.16-19.69), and 14/07 (12.02-18.64) pmol/L for FT4, respectively. The frequency of elevated serum TSH was 9.0% (6.6% subclinical, 2.4% overt hypothyroidism). The frequency of low serum TSH was 0.6%. The frequency of positive TPOAb was 7.6%. Results of this study have clarified that despite iodine sufficiency of school children in Iran, pregnant women have moderate iodine deficiency and need iodine supplementation.

Knowledge and practices of iodized salt consumption among pregnant women in Galle district

Introduction: Sri Lanka introduced national salt iodization programme in 1995 to control iodine deficiency disorders (IDD) as iodized salt is the main source of iodine in the population. Although Sri Lanka achieved a satisfactory control of IDD in 2005, a recent study showed that iodine nutrition in pregnant women in Sri Lanka is far below the WHO recommendation. Lack of knowledge on iodized salt and improper practices of its usage may cause iodine deficiency during pregnancy. Methods: Study was conducted in Bope-Poddala health division of Galle District in the Southern province. Pregnant women (n=425) with gestational age = Results : Forty percent of pregnant women in the sample had poor knowledge on iodized salt and the importance of iodine in the diet. Less than 50% of subjects were aware of bad consequences of maternal iodine deficiency on their babies and about 50% of them had improper practices on iodized salt usage. A poor correlation between the good knowledge and proper practices, were observed. Conclusion: Overall knowledge about iodine and iodized salt is not satisfactory and the health educational programmes expressing the importance of eliminating IDD at various levels is important to prevent iodine deficiency during pregnancy. Galle Medical Journal 2015 20(1): 10-16

Inadequate Iodine Nutrition of Pregnant Women in an Area of Iodine Sufficiency

Inadequate Iodine Nutrition of Pregnant Women in an Area of Iodine Sufficiency

Limited knowledge about folic acid and iodine nutrition in pregnant women reflected in supplementation practices

AbstractAimIn order to reduce the risk of neural tube defects (NTDs) and iodine deficiency in pregnancy, the National Health and Medical Research Council recommends that pregnant women supplement their diet with folic acid and iodine. This study aimed to identify the knowledge, attitudes and practices of pregnant women regarding intake of these nutrients in order to assess whether women are adequately exposed to this health message.MethodsOne hundred and fifty‐two conveniently sampled pregnant women residing in a regional area of New South Wales, Australia, completed a pretested questionnaire on knowledge and practices regarding nutritional supplement use during pregnancy and dietary sources of folic acid and iodine.ResultsEighty‐two per cent of women reported using supplements during their pregnancy, with the majority (67.7%) taking supplement brands containing both folic acid and iodine. Supplement use was significantly higher among women in the highest household income category (30.8 vs 69.2%; P = 0.001). Seventy‐six per cent of the participants correctly identified NTDs to be associated with inadequate intake of folic acid, whereas only 40% correctly identified health problems associated with inadequate iodine intake. Women's knowledge of dietary sources of folic acid and iodine was limited.ConclusionsA third of the pregnant women surveyed were not adhering to clinical recommendations for supplement use during pregnancy, and many had knowledge deficits with regard to the need for an adequate dietary intake of folic acid and iodine from both food and supplements during pregnancy.

Iodine nutrition in pregnant women in the Oviedo area. Is iodine supplementation required?

Abstract Background and objective In Asturias, where iodine deficiency was eradicated in school children by the year 2000, iodine deficiency persisted in pregnant women, who were recommended to use of iodine supplementation. The aim of this study was to determine the iodine nutrition of pregnant women in our area and whether or not iodine supplements are needed. Material and methods Throughout May and June 2013 we studied the iodine nutrition and thyroid function during the first trimester of pregnancy in 173 women in the health area of Oviedo. Results The median urinary iodine was 197 μg/L. Iodinated supplements were used by 47% of women, which had a yoduria median higher than those not taking iodinated supplements (247 vs 138 μg/L; p Conclusions Iodinated supplements seem unnecessary nowadays in pregnant women of Oviedo who regularly take iodized salt and our recommendation in these cases should be to continue the use of iodized salt in the recommended amounts during pregnancy and consume at least two daily servings of milk or dairy products.

Nutrición de yodo en mujeres embarazadas del área de Oviedo. ¿Es necesaria la suplementación con yodo?

Background and objectiveIn Asturias, where iodine deficiency was eradicated in school children by the year 2000, iodine deficiency persisted in pregnant women, who were recommended to use of iodine supplementation. The aim of this study was to determine the iodine nutrition of pregnant women in our area and whether or not iodine supplements are needed. Material and methodsThroughout May and June 2013 we studied the iodine nutrition and thyroid function during the first trimester of pregnancy in 173 women in the health area of Oviedo. ResultsThe median urinary iodine was 197μg/L. Iodinated supplements were used by 47% of women, which had a yoduria median higher than those not taking iodinated supplements (247 vs. 138μg/L; p<.001), and also a higher TSH (2.30 vs 1.94 mU/L) although not significantly different. Yoduria was also higher in women who took more than 2 servings of dairy products (median: 230μg/L) than those who took less (median: 191μg/L). Within the group of women who were not taking iodine supplements, those regularly using iodized salt in the kitchen (47%) had a median urinary iodine concentration of 190μg/L indicating iodine sufficiency. ConclusionsIodinated supplements seem unnecessary nowadays in pregnant women of Oviedo who regularly take iodized salt and our recommendation in these cases should be to continue the use of iodized salt in the recommended amounts during pregnancy and consume at least two daily servings of milk or dairy products.

Effects of iodine deficiency and supplementation during pregnancy on offspring neurobehavioral development

Consuming an adequate amount of iodine during pregnancy is critical for fetal neurologic development.Even a mild deficiency can impair cognitive ability.The World Health Organization recently has increased their recommended iodine intake during pregnancy from 200 to 250 μg/d and suggested that a median urinary iodine concentration of 150 ～ 249 μg/L indicates adequate iodine intake in pregnant women.Whether mild-to-moderate maternal iodine deficiency produces more subtle changes in cognitive function in offspring is unclear;no controlled intervention studies have measured long-term clinical outcomes.This review summarizes the iodine nutrition of pregnant women,and the effects of iodine deficiency in pregnancy on neurodevelopment in the child.To prevent fetal damage,iodine should be given before or early in pregnancy. Key words: Pregnant women; Iodine deficiency; Iodine supplementation; Offspring neurobehavioral development

Iodine nutrition of pregnant women in India: evidence of significant iodine deficiency

Iodine nutrition of pregnant women in India: evidence of significant iodine deficiency

Maternal thyroid function in different conditions of iodine nutrition in pregnant women exposed to mild-moderate iodine deficiency: an observational study

We examined the effect of different conditions of nutritional iodine intake on maternal thyroid function throughout gestation in a cohort of healthy, anti-thyroid antibody-negative women from a mild-moderately iodine-deficient (ID) area. Observational cohort study. The study included 168 women receiving prenatal preparations containing 150 μg of iodine from early pregnancy (150-I group); 105 women who had regularly used (>2 years) iodized salt prior to becoming pregnant (I-salt group); 160 women neither taking iodine supplements nor using iodized salt (no-I group). Maternal TSH, FT3 and FT4 were determined throughout gestation. Mean TSH concentrations were higher among the 150-I women than in the remaining two groups, and in a high proportion of them, TSH values were found to exceed the upper limit for gestational age. Conversely, the prevalence of low free-thyroxine levels in the 150-I women was similar to that observed in the I-salt women and markedly lower than that recorded for the no-I group. The regular use of iodine-containing supplements proved effective in reducing the risk of inappropriately low FT4 levels during pregnancy. The observed TSH increase in 150-I women may be because of a transient stunning effect on the thyroid gland, occurring as a result of the abrupt increase in daily iodine intake. Whilst the importance of gestational iodine supplementation is undisputed, we believe that in mild-moderately ID areas, women considering conception should be advised to take iodine supplementation for several months prior to pregnancy.

Patterns of Iodine Intake and Urinary Iodine Concentrations During Pregnancy and Blood Thyroid-Stimulating Hormone Concentrations in the Newborn Progeny

Appropriate maternal intake of iodine during pregnancy is essential for maternal thyroxine production and thyroid status of the fetus. It should be possible to enhance iodine intake during pregnancy by using iodine fortified salt or taking iodine supplements. In the present report we determined the status of iodine nutrition in pregnant women who were stratified on the basis of their history of taking or not taking iodized salt or iodine supplements. The study was performed in Toledo (Spain), a region in which prior studies have noted borderline iodine sufficiency. Iodine nutrition was assessed by measuring urinary iodine concentration (UIC) and neonatal thyrotropin (TSH). UIC was measured in 525 pregnant women. They were grouped according to their history of iodine intake. Diet Group 1 patients (n = 69) did not take iodized salt or iodine supplements during pregnancy. Diet Group 2 patients (n = 75) took iodized salt but not iodine supplements during pregnancy. Diet Group 3 patients (n = 381) took iodine supplements during pregnancy. Plasma determinations included TSH, free thyroxine, thyroid peroxidase antibody, and thyroglobulin antibody. UIC was measured in a single urine sample from all the pregnant women. Neonatal TSH was measured in capillary spot blood from all the neonates as part of a screening for congenital metabolic abnormalities. The median UIC in all subjects was 164 μg/L (interquartile range [IR]: 116-245). The median UICs in Diet Groups 1, 2, and 3 were 134.5 (IR: 90-196), 146 (IR: 103-205), and 183 (IR: 124-261) μg/L, respectively (p = not significant [NS] for Diet Group 1 vs. 2; p < 0.01 for Diet Group 2 vs. 3; all other comparisons NS). The median (IR) TSH of the neonates in all Diet Groups was 1.0 (IR: 0.7-1.6) μU/mL. Only 2 neonates had blood TSH concentrations >5 mU/L. Neonatal blood TSH concentrations were similar in all Diet Groups. In a region with a history of borderline iodine deficiency the UICs were below 150 μg/L in a substantial percentage of pregnant women who did not take iodine supplements, regardless of whether or not they took iodized salt. Our results support the use of iodine supplements from the start of the pregnancy, or even before pregnancy in women who live in regions with a history of even small degrees of iodine deficiency. In addition, neonate TSH screening is not the best tool to assess whether the iodine status in populations is ideal.

Inadequate iodine nutrition of pregnant women from Extremadura (Spain)

To evaluate the iodine nutrition of the pregnant women of the Spanish Autonomous Community Extremadura. There are approximately 10,000 births per year in Extremadura, which historically contains areas with endemic goiter (Las Hurdes). Population study in which a representative sample of pregnant women of the general population was analyzed, along with another sample of pregnant women from traditionally goitrogenic areas. With the collaboration of selected health centers, an additional sample of blood and urine was obtained within the primary health care pregnancy-monitoring program; these samples were sent to a single central laboratory. Biochemistry: determination of iodine and creatinine in urine, and serum concentrations of thyroxine, free thyroxine, tri-iodothyronine, TSH, thyroglobulin, and two anti-thyroid antibodies. Each parameter was measured by means of a single specific RIA. Changes between the first trimester and later stages of pregnancy of all biochemical variables studied corresponded with those described for other European areas with a comparable iodine nutrition. Using the urinary iodine concentration value as an indicator of iodine ingestion, it was found that in the first trimester of pregnancy six out of ten women from Extremadura ingested less than the currently recommended amount (250 microg I/day), and approximately three out of ten of these women ingested less than half of this amount. It is imperative to implement in all Extremadura the generalized and controlled use of complements that contain 200-250 microg I/day throughout pregnancy and, if possible, before.

The NAS Perchlorate Review: Second-Guessing the Experts

The Committee to Assess the Health Implications of Perchlorate Ingestion [National Academy of Sciences (NAS)] released its final report [National Research Council (NRC) 2005] in January 2005, recommending a reference dose (RfD) for perchlorate of 0.0007 mg/kg-day. In a commentary published online on 25 May 2005, Ginsberg and Rice (2005) criticized the adequacy of the NAS committee’s scientific deliberations, mischaracterizing the studies reviewed by the committee and second-guessing its conclusions. Ginsberg and Rice (2005) implied that the U.S. Environmental Protections Agency’s (EPA’s) previous draft RfD of 0.00003 mg/kg-day (U. S. EPA 2002)—and by inference the Massachusetts perchlorate risk assessment [Massachusetts Department of Environmental Protection (Mass DEP) 2004] that mirrored the U.S. EPA’s approach and which Ginsberg and Rice peer reviewed—is more scientifically defensible. The NAS committee was composed of 15 leading physicians and scientists with combined range of expertise to evaluate every scientific aspect of the perchlorate database and of the U.S. EPA’s assessment of that database. The makeup of this committee and its credentials are available on the NAS website (NAS 2004). The NAS committee studied and deliberated for more than 15 months before issuing its report. Those deliberations included three public meetings during which it accepted verbal and/or written comments from the U.S. EPA, other government agencies, industry, states, environmental groups, and attorneys. After careful study and consideration of the scientific studies that formed the basis for the U.S. EPA’s 2002 draft RfD as well as the 2004 Massachusetts risk assessment (Mass DEP 2004), the NAS committee considered several of the animal studies … to be flawed in their design and execution. Conclusions based on those studies, particularly the neurodevelopmental studies, were not supported by the results of the studies. Although Ginsberg and Rice (2005) implied that the NAS committee should have considered the threshold for measurable iodine uptake inhibition “adverse” and that the NAS inadvertently left out the “A” in NOAEL (no observed adverse effect level), the committee decisively stated that “inhibition of iodide uptake by the thyroid clearly is not an adverse effect.” The committee carefully considered the issue of a NOEL (no observed effect level) and a NOAEL. Based on a clinical study of patients receiving perchlorate long term, the NAS established the NOAEL as 0.4 mg/kg-day (57 times higher than its identified NOEL). Ginsberg and Rice (2005) further expressed concerns regarding perchlorate in breast milk and the subsequent possibility of decreased breast milk iodine, citing Kirk et al. (2005) and Gibbs (2004). Kirk et al. (2005) reported perchlorate and iodide levels in breast milk samples and noted that “if we take all the available data, there is no meaningful correlation between the perchlorate and iodide levels in breast milk.” The study from Chile that Ginsberg and Rice refer to as Gibbs (2004) is now published as Tellez et al. (2005). The study found that iodine nutrition of pregnant women in Chile is very similar to that in the United States. Tellez et al. (2005) found no maternal or neonatal perchlorate-related thyroid effects or decreases in breast milk iodine with perchlorate doses spanning the 0.0007–0.007 mg/kg-day range. Ginsberg and Rice (2005) argued that perchlorate database deficiencies require an additional uncertainty factor of 3–10 because of key data gaps, citing breast milk concerns and the extrapolation from a 14-day exposure study to chronic exposure. The NAS committee (NRC 2005) considered this and concluded that if inhibition of iodide uptake by the thyroid is duration-dependent, the effect should decrease rather than increase with time, because compensation would increase the activity of the sodium-iodide symporter and therefore increase iodide transport into the thyroid. Evidence has subsequently shown this to be the case (Braverman et al. 2005). The California EPA perchlorate risk assessment (California EPA 2004) relied on the same studies as the NRC report (NRC 2005). The “point of departure” was based on iodine uptake inhibition by Greer et al. (2002), and a total uncertainty factor of 10 was applied to account for interindividual variability. After reviewing the NRC report (NRC 2005), the California EPA elected not to change its risk assessment or public health goal (California EPA 2005). In summary, the concerns presented by Ginsberg and Rice (2005) have already been addressed thoroughly by experts on perchlorate and thyroid toxicology and were found to be unsubstantiated. The NAS committee and other experts came to this conclusion based on a comprehensive review of the science in the field, not based entirely on an individual study, which has been mischaracterized by Ginsberg and Rice.