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Seaweeds and soy are two commonly eaten foods in Asia. Both have been reported to affect thyroid function, seaweed because of its iodine content and soy because of its goitrogenic effect. Twenty-five healthy postmenopausal women (mean age 58 years) completed a double-blinded randomized crossover study. Ten capsules (5 g/day) of placebo or seaweed (Alaria esculenta), providing 475 microg of iodine/day, were consumed daily for 7 weeks. A powdered soy protein isolate (Solae Co., St. Louis, MO), providing 2 mg of isoflavones/kg of body weight, was given daily during the last week of each treatment arm. On average, this provided 141.3 mg of isoflavones/day and 67.5 g of protein/day. Blood samples and 48-hour urine samples were collected before and after each intervention period, and urinary I/C (microg of iodine/g of creatinine) and serum thyroxine, free thyroxine index, total triiodothyronine, and thyroid stimulating hormone (TSH) were measured. Seaweed ingestion increased I/C concentrations (P < .0001) and serum TSH (P < .0001) (1.69 +/- 0.22 vs. 2.19 +/- 0.22 microU/mL, mean +/- SE). Soy supplementation did not affect thyroid end points. Seven weeks of 5 g/day seaweed supplementation was associated with a small but statistically significant increase in TSH. Soy protein isolate supplementation was not associated with changes in serum thyroid hormone concentrations. [ABSTRACT FROM AUTHOR]

Objective: To develop a set of minimum clinical guidelines for use by primary care physicians in the evaluation and management of patients with hyperthyroidism and hypothyroidism.Participants: Guidelines were developed by a nine-member ad hoc Standards of Care Committee of the American Thyroid Association (the authors of this article). The participants were selected by the committee chair and the president of the American Thyroid Association on the basis of their clinical experience. The committee members represented different geographic areas within the United States, in order to take into account different practice styles.Evidence: Guidelines were developed on the basis of expert opinion of the participants, as well as on available published information.Consensus Process: Input was obtained from all of the participants, each of whom wrote an initial section of the document. A complete draft document was then written by three participants (P.A.S., D.S.C., and E.G.L.) and resubmitted to the entire committee for revision. The revised document was then submitted to the entire membership of the American Thyroid Association for written comments, which were then reviewed (mainly by P.A.S., D.S.C., and E.G.L.). Many of the suggestions of the American Thyroid Association members were incorporated into the final draft, which was then approved by the Executive Council of the American Thyroid Association. The entire process, from initial drafts to final approval, took approximately 18 months.Conclusions: A set of minimum clinical guidelines for the diagnosis and treatment of hyperthyroidism and hypothyroidism were developed by consensus of a group of experienced thyroidologists. The guidelines are intended to be used by physicians in their care of patients with thyroid disorders, with the expectation that more effective care can be provided, and at a cost savings. [ABSTRACT FROM AUTHOR]

Now that an extremely sensitive diagnostic test for thyroid disorders is available, both subclinical and clinical disease can be readily detected. That opens the door to an array of effective treatments. [ABSTRACT FROM AUTHOR]

We report the cases of 3 infants with congenital hypothyroidism detected with the use of our newborn screening program, with evidence supporting excess maternal iodine ingestion (12.5 mg/d) as the etiology. Levels of whole blood iodine extracted from their newborn screening specimens were 10 times above mean control levels. Excess iodine ingestion from nutritional supplements is often unrecognized. [ABSTRACT FROM AUTHOR]

Incidence of the metabolic syndrome is increasing worldwide, with notable exceptions of some Asian countries where seaweeds are commonly consumed. 13 men (mean age 47.4 +/- 9.9 yr) and 14 women (average age 45.6 +/- 12.2 yr) with at least one symptom of the metabolic syndrome were recruited in Quito Ecuador to a randomized double-blinded placebo-controlled trial. Subjects were assigned to either Group 1 (1 m placebo, followed by 1 m 4 g/d seaweed [Undaria pinnatifida]) or Group 2 (1 m of 4 g/d seaweed, followed by 1 m of 6 g/d of seaweed). Blood pressure, weight, waist circumference, inflammation biomarkers, and lipids were measured monthly. Repeated measures analysis of variance with Tukey's multiple comparison tests were used for statistical analysis. In Group 2, systolic blood pressure decreased 10.5 mmHg after a month of 6 g/d seaweed (95% CI: 4.1, 16.8 mmHg; p< 0.05), primarily in subjects with high-normal baseline blood pressure. Waist circumference changed only for women participants, with a 2.4 cm decrease in Group 1 after treatment with placebo (95% CI: 1.0, 3.7 cm; p< 0.01). In Group 2, women had a mean decrease of 2.1 cm after 4 g/d (95% CI: 0.4, 3.7 cm; p< 0.05) and a further 1.8 cm decrease after 1 m 6 g/d seaweed (95 % CI: 0.1, 3.4, p< 0.05). No other changes were observed. Consumption of 4 to 6 g/d seaweed, typical for most people in Japan, may be associated with low metabolic syndrome prevalence. [ABSTRACT FROM AUTHOR]

Introduction: Epoprostenol, a synthetic prostaglandin I2 (PGI 2 ) analog, has been the mainstay of treatment for severe pulmonary arterial hypertension (PAH) for the last two decades. Treprostinil, another synthetic prostaglandin analog, and selexipag, an oral selective Inositol Phosphate (IP) prostacyclin receptor agonist, have also been approved for treatment of PAH. Prostacyclin and its analogs cause a variety of side effects in patients with PAH; however, thyroid dysfunction is rarely reported., Methods: After treating an index case of thyroid dysfunction occurring after initiation of epoprostenol, we reviewed our databases of PAH patients treated with epoprostenol, treprostinil or selexipag to identify the occurrence of this association., Results: We identified six cases of thyroid dysfunction in our cohort: five after initiation of an intravenous prostacyclin (epoprostenol) and one after initiation of an oral prostacyclin receptor agonist (selexipag). Four of the patients presented with hyperthyroidism and two with a large autoimmune goiter. Graves' disease was seen in three patients, Hashimoto's disease in two patients and thyrotoxicosis in one patient., Conclusion: Therapy with medications targeting the prostacyclin pathway is a potential risk factor for the development of symptomatic thyroid disease.

Background: As iodine is a requisite micronutrient for infant brain development, infants are at risk for iodine deficiency during the weaning period when their diet transitions from milk (breast-milk, infant formula, or follow-on formula) to solid food. Dietary iodine intake during this weaning period is likely minimal, as the iodine content of commercial baby food is not regulated, and the addition of salt to baby food is not recommended. This study reports the current status of iodine nutrition among weaning infants in the United States., Methods: Subjects (n = 60; 50% Caucasian, 30% black) were infants <12 months of age who were fed any combination of formula and/or baby food. Samples of all formula and food consumed in the previous 24 hours and a spot urine sample from each infant were obtained for the measurement of iodine. The estimated quantities of ingested formula and baby food were summed from a food diary recorded by the infants' parents., Results: The mean age of the infants was 6.3 ± 3.5 months. The median urinary iodine concentration (UIC) was 117 μg/L (range 26.9-1302.8 μg/L). Estimated daily iodine intake obtained from the measured iodine content in infant formula/foods was 89 μg (range 0-288 μg). There was a positive correlation between the infants' UIC and the iodine content in the consumed foods (r = 0.4, p < 0.001)., Conclusions: Although the median UIC of infants fed a combination of infant formula and baby food would meet the criteria for iodine sufficiency in a larger sample, those consuming the lowest quartile of iodine-containing nutritional sources had a median UIC <100 μg/L.

Background: Iodine is important for thyroid hormone synthesis, and iodine deficiency in pregnancy may impair fetal neurological development. As perchlorate and thiocyanate inhibit sodium-iodide symporter reducing the transport of iodine from circulation into the thyroid follicular cells, environmental exposure to these substances in pregnancy may impair maternal thyroid hormone synthesis. We aimed to explore the impact of perchlorate and thiocyanate exposure on thyroid status in a cohort of pregnant mothers from South West England., Methods: Urine samples were obtained from 308 women participating in a study of breech presentation in late pregnancy. They had no known thyroid disease and a singleton pregnancy at 36-38 weeks gestation. Samples were analysed for urinary concentrations of iodine (UIC), perchlorate (UPC) and thiocyanate (UTC). Blood samples were taken for free T4 (FT4), thyrotropin (TSH) and thyroid peroxidase antibodies (TPO-Ab). Baseline data included age, parity, smoking status, ethnicity and BMI at booking. Following delivery, data on offspring's sex, gestational age at birth and birthweight were collected., Results: Participants had a mean (SD) age 31 (5) years, median (IQR) BMI 24.4 (22.0, 28.3) kg/m 2 , 42% were primiparous, 10% were smokers, and 96% were Caucasian. Median UIC was 88 μg/l, and 174/308 (57%) women had UIC < 100 μg/l. Log transformed UPC negatively correlated with FT4, but not with TSH, in the whole cohort ( r  = - 0.12, p  = 0.03) and in the subgroup of women with UIC < 100 μg/l ( r  = - 0.15, p  = 0.04). Regression analysis with the potential confounders (TPO-Ab status, UIC and UTC) identified UPC to be negatively associated with FT4 ( p  = 0.01). There was no correlation between UTC and FT4 or TSH. Maternal UPC or UTC was not associated with offspring birthweight., Conclusion: Environmental perchlorate exposure is negatively associated with circulating FT4 levels in third trimester pregnant women. This may have an adverse impact on neurocognitive development of the fetus., Competing Interests: The study was approved by the National Research Ethics Service (NRES) Committee South West – Exeter, and all participants gave informed written consent.All authors provide consent for this publication.LEB and ENP have received research funding from Sociedad Química y Minera de Chile.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Objective: To conduct a more robust examination of perchlorate exposure on iodide uptake inhibition (IUI) using pooled data from four clinical studies of perchlorate exposure., Methods: To establish a response threshold for IUI, data were analyzed using segmented linear regression and benchmark dose (BMD) analysis., Results: Segmented linear regression applied to data for 69 subjects representing nine doses identified a breakpoint corresponding to a change in the slope of the dose-response relationship of 3.0 mg/d perchlorate. The estimated BMD for a 20% decrease in iodine uptake was 2.3 mg/d, with a lower 95% confidence interval limit of 1.6 mg/d., Conclusions: A threshold dose for IUI from perchlorate exposure of 1.6 to 3.0 mg/d (0.021 to 0.038 mg/kg d) was estimated using two modeling approaches. These estimates are slightly higher than the lowest observed effect level of 0.02 mg/kg d from the Greer Study.

Background: Prenatal exposure to some per- and polyfluoroalkyl substances (PFASs) may disrupt maternal and neonatal thyroid function, which is critical for normal growth and neurodevelopment., Objectives: We examined associations of PFAS exposure during early pregnancy with maternal and neonatal thyroid hormone levels., Methods: We studied 732 mothers and 480 neonates in Project Viva, a longitudinal prebirth cohort in Boston, Massachusetts. We quantified six PFASs, including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), and maternal thyroid hormones [thyroxine (T 4 ), Free T 4 Index (FT 4 I), thyroid stimulating hormone (TSH)] in plasma samples collected at a median 9.6 wk gestation and neonatal T 4 levels from postpartum heel sticks. We estimated associations of PFAS concentrations with thyroid hormone levels using covariate-adjusted linear regression models and explored effect measure modification by maternal thyroid peroxidase antibody (TPOAb) status and infant sex., Results: PFAS concentrations were not associated with maternal T 4 , but PFOA, perfluorohexane sulfonate (PFHxS), and 2-(N-methyl-perfluorooctane sulfonamido) acetate (MeFOSAA) were inversely associated with maternal FT 4 I [e.g., -1.87% (95% confidence interval (CI): -3.40, -0.31) per interquartile (IQR) increase in PFOA]. PFAS concentrations [PFOA, PFOS, and perfluorononanoate (PFNA)] were inversely associated with TSH levels in TPOAb-positive women only. Prenatal PFOS, PFOA, and PFHxS concentrations were inversely associated with T 4 levels in male [e.g., PFHxS, quartile 4 vs.1: -2.51μg/dL (95% CI: -3.99, -1.04 )], but not female neonates [0.40μg/dL (95% CI: -0.98, 1.79)]., Conclusions: In this study, prenatal exposure to some PFASs during early pregnancy was inversely associated with maternal FT 4 I and neonatal T 4 in male infants. These results support the hypothesis that prenatal exposure to PFASs influences thyroid function in both mothers and infants. https://doi.org/10.1289/EHP2534.

Background: Iodine is an essential micronutrient for thyroid hormone production. Adequate iodine intake and normal thyroid function are important during early development, and breastfed infants rely on maternal iodine excreted in breast milk for their iodine nutrition. The proportion of women in the United States of childbearing age with urinary iodine concentration (UIC) <50 μg/L has been increasing, and a subset of lactating women may have inadequate iodine intake. UIC may also be influenced by environmental exposure to perchlorate and thiocyanate, competitive inhibitors of iodine transport into thyroid, and lactating mammary glands. Data regarding UIC in U.S. lactating women are limited. To adequately assess the iodine sufficiency of lactating women and potential associations with environmental perchlorate and thiocyanate exposure, we conducted a multicenter, cross-sectional study of urinary iodine, perchlorate, and thiocyanate concentrations in healthy U.S. lactating women., Methods: Lactating women ≥18 years of age were recruited from three U.S. geographic regions: California, Massachusetts, and Ohio/Illinois from November 2008 to June 2016. Demographic information and multivitamin supplements use were obtained. Iodine, perchlorate, and thiocyanate levels were measured from spot urine samples. Correlations between urinary iodine, perchlorate, and thiocyanate levels were determined using Spearman's rank correlation. Multivariable regression models were used to assess predictors of urinary iodine, perchlorate, and thiocyanate levels, and UIC <100 μg/L., Results: A total of 376 subjects (≥125 from each geographic region) were included in the final analyses [mean (SD) age 31.1 (5.6) years, 37% white, 31% black, and 11% Hispanic]. Seventy-seven percent used multivitamin supplements, 5% reported active cigarette smoking, and 45% were exclusively breastfeeding. Median urinary iodine, perchlorate, and thiocyanate concentrations were 143 μg/L, 3.1 μg/L, and 514 μg/L, respectively. One-third of women had UIC <100 μg/L. Spot urinary iodine, perchlorate, and thiocyanate levels all significantly positively correlated to each other. No significant predictors of UIC, UIC <100 μg/L, or urinary perchlorate levels were identified. Smoking, race/ethnicity, and marital status were significant predictors of urinary thiocyanate levels., Conclusion: Lactating women in three U.S. geographic regions are iodine sufficient with an overall median UIC of 143 μg/L. Given ubiquitous exposure to perchlorate and thiocyanate, adequate iodine nutrition should be emphasized, along with consideration to decrease these exposures in lactating women to protect developing infants.

Competing Interests: The authors declare no conflict of interest.

Objective: Iodine is essential for thyroid hormone synthesis, and iodine deficiency may result in thyroid disorders including goiter and hypothyroidism. Patients on long-term enteral nutrition (EN) or parenteral nutrition (PN) may be at risk for micronutrient deficiencies. The recommended daily allowance for iodine intake is 150 μg for nonpregnant adults. However, there is no current consensus among scientific societies regarding the quantity of iodine to be added in adult EN and PN formulations. The objective of this study was to determine the iodine content of U.S. adult enteral and parenteral nutrition solutions. This study also aimed to determine whether adult patients in the United States who are receiving long-term artificial nutrition may be at risk for iodine deficiency., Methods: Ten enteral nutrition solutions and 4 parenteral nutrition solutions were evaluated. The iodine contents of these solutions were measured spectrophotometrically and compared to the labeled contents., Results: Measured and labeled EN iodine contents were similar (range 131-176 μg/L and 106-160 μg/L, respectively). In contrast, PN formulas were found to contain small, unlabeled amounts of iodine, averaging 27 μg/L., Conclusion: Typical fluid requirements are 30 to 40 mL/kg/day for adults receiving either total EN (TEN) or total PN (TPN). Adults on long-term TEN likely consume enough servings to meet their daily iodine requirements. However, patients on long-term TPN would require on average 5.6 L PN/day to meet the recommended daily allowance of iodine. This volume of PN is far in excess of typical consumption. Thus, U.S. patients requiring long-term TPN may be at risk for iodine deficiency., Abbreviations: EN = enteral nutrition; PN = parenteral nutrition; TEN = total enteral nutrition; TPN = total parenteral nutrition; UIC = urinary iodine concentration.

Triphenyl phosphate (TPHP) is a commonly used organophosphate flame retardant and plasticizer with widespread human exposure. Data on health effects of TPHP are limited. Recent toxicological studies suggest TPHP may alter thyroid function. We used repeated measures to assess the temporal variability in urinary concentrations of the TPHP metabolite, diphenyl phosphate (DPHP), and to examine relationships between DPHP concentrations and thyroid hormones. We sampled 51 adults at months 1, 6, and 12 from 2010 to 2011. Urine samples were analyzed for DPHP. Serum samples were analyzed for free and total thyroxine (fT 4 , TT 4 ), total triiodothyronine (TT 3 ), and thyroid stimulating hormone (TSH). We assessed variability in DPHP using intraclass correlation coefficients (ICCs) and kappa statistics. We used linear mixed-effects models to examine associations between DPHP and thyroid hormones. DPHP was detected in 95% of urine samples. Mean DPHP concentrations were 43% higher in women than men. DPHP showed high within-subject variability (ICC range, 0.13-0.39; kappa range, 0.16-0.39). High versus low (≥2.65 vs. <2.65ng/mL) DPHP in all participants was associated with a 0.43μg/dL (95% confidence interval: 0.15, 0.72) increase in mean TT 4 levels. In sex-stratified analyses, high versus low DPHP was associated with a 0.91μg/dL (95% CI: 0.47, 1.36) increase in mean TT 4 in women. The association was attenuated in men (βeta=0.19; 95% CI: -0.15, 0.52). We found no significant associations between DPHP and fT 4 , TT 3 , or TSH. We found evidence that TPHP exposure may be associated with increased TT 4 levels, especially in women., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Iodine deficiency is a major public-health problem throughout the world, especially for pregnant women, and it is considered the most common cause of preventable intellectual impairment. In the United States, iodine status in pregnant women is considered mildly deficient. Therefore, the Endocrine Society, the American Thyroid Association, the Teratology Society, and the American Academy of Pediatrics recommend that women receive prenatal vitamins containing 150 μg of iodine daily during preconception, pregnancy, and lactation. The objectives of this study were to evaluate awareness of iodine nutrition among obstetricians and midwives in the United States, and to document current clinical practice regarding recommendations for iodine supplementation for women during preconception, pregnancy, and lactation., Methods: All midwife members of the American College of Nurse-Midwives (ACNM) and all obstetrician members of the American Medical Association (AMA) were invited to participate in a web-based survey., Results: A total of 199 midwives and 277 obstetricians participated in the survey. One third of both obstetricians and midwives considered iodine status in U.S. pregnant women to be deficient. Although almost all obstetricians and midwives would recommend prenatal multivitamins, most reported rarely or never recommending iodine-containing multivitamins for women planning pregnancy (68.7% and 70.2%, respectively), pregnant women (66% and 67.1%), or lactating women (68.7% and 71.7%). Of the respondents who did report prescribing iodine-containing supplements, 85% recommended supplementation during the first trimester and 75-80% during the second and third trimesters. However, of those who did recommend iodine supplementation, only 45% would prescribe the recommended 150 μg of iodine daily during pregnancy. Overall, 75% of U.S. obstetricians and midwives do not recommend or would recommend an inadequate amount of iodine during preconception, pregnancy, and lactation., Conclusions: Despite the important consequences of iodine deficiency for pregnant women and the recommendations of many medical societies, the majority of U.S. obstetricians and midwives who participated in this survey do not recommend iodine-containing vitamins in women planning pregnancy, during pregnancy, and during lactation.

Introduction: Iodine deficiency in pregnancy may impair foetal neurological development. The UK population is generally thought to be iodine sufficient; however, recent studies have questioned this assumption. Our study aimed to explore the prevalence of iodine deficiency in a cohort of pregnant mothers from South-West England., Methods: Urine samples were obtained from 308 women participating in a study of breech presentation in late pregnancy. They had no known thyroid disease and a singleton pregnancy at 36-38 weeks' gestation. Samples were analysed for urinary iodine concentrations (UIC). Baseline data included age, parity, smoking status, ethnicity, body mass index (BMI) at booking, prenatal vitamin use and a dietary questionnaire. There was no difference in median UIC between women with (n = 156) or without (n = 152) a breech presentation (P = 0·3), so subsequent analyses were carried out as a combined group., Results: Participants had a mean (SD) age 31(5) years, median (IQR) BMI 24·4 (22·0, 28·3) kg/m 2 ; 42% were primiparous, 10% smoked during pregnancy, and 35% took iodine-containing vitamins. Ninety-six per cent were Caucasian. Median (IQR) UIC was 88·0 (54·3, 157·5) μg/l, which is consistent with iodine deficiency by WHO criteria. A total of 224/308 (73%) of women had UIC values <150 μg/l. Increasing milk intake was associated with higher UIC (P = 0·02). There was no difference in median (IQR) UIC between those women who took iodine-containing vitamins (n = 108) and those who did not (n = 200): 88 (54, 168) vs 88 (54, 150) μg/l, P = 0·7., Conclusion: Iodine deficiency in pregnancy is common in South-West England. Measures to develop optimum prevention and treatment strategies are urgently needed., (© 2016 John Wiley & Sons Ltd.)