Iodine Content in Meal Replacements in the United States

ObjectiveIodine is essential for thyroid hormone production. The recommended dietary allowance for iodine in nonpregnant adults is 150 μg/d. However, most product labels do not list the iodine content. Meal replacements are not required to contain specific vitamins and minerals. Nevertheless, they are often marketed as good and convenient sources of a balanced nutrition. In this study, we aimed to assess the iodine content in meal replacements to determine how they may contribute to iodine deficiency or excess.MethodsTwenty seven meal replacements from supermarkets in the Boston area were collected. The iodine concentration of each meal replacement was measured spectrophotometrically. Iodine content in meal replacements were compared according to form (liquid, bar, and powder) and type (vegan and nonvegan).ResultsThe overall mean ± SD iodine content was 49.7 ± 125.4 μg/serving. However, 1 meal replacement was an outlier and had 671.9 μg iodine per serving. Mean iodine content differed between forms and was highest for liquids (mean ± SD: 37.4 ± 6.5 μg/serving). Nonvegan meal replacements had a higher mean iodine content than vegan meal replacements (mean ± SD: 31.6 ± 15.78 μg/serving).ConclusionAll of the meal replacements contained detectible amounts of iodine regardless of whether it was listed on their labels (41% did not list iodine). Overall, the meal replacements in this study were found to be good sources of iodine. However, consumers should be aware that packaging labels may not accurately reflect the amount of iodine present.     

The Iodine Status and Prevalence of Thyroid Disorders Among Women of Childbearing Age in China: National Cross-sectional Study

ObjectiveMandatory universal salt iodization in China was implemented 20 years ago. However, the current iodine status and prevalence of thyroid disorders among childbearing-age women are unknown.MethodsA nationally representative cross-sectional study with 26 166 enrolled participants aged 18 to 49 years from all 31 provincial regions of mainland China was performed. The participants were given a questionnaire and underwent B-mode ultrasonography of the thyroid. The serum concentrations of thyroid hormones and thyroid antibodies and the urinary iodine concentration (UIC) were measured.ResultsThe median UIC was 178.7 μg/L, indicative of adequate iodine status. pHowever, 19.04% and 19.87% of the participants were classified as having iodine deficiency and excessive iodine, respectively. The weighted prevalence of thyroid disorders was as follows: 1.08% had overt hyperthyroidism, 0.58% had subclinical hyperthyroidism, 0.76% had Graves disease, 1.28% had overt hypothyroidism, 14.28% had subclinical hypothyroidism, 13.53% were positive for thyroid peroxidase antibodies, and 14.55% were positive for thyroglobulin antibodies. Excessive iodine and overweight were associated with higher odds of subclinical hypothyroidism. A family history of thyroid disorders and an age between 40 and 49 years were significantly associated with higher odds of positivity for thyroid peroxidase antibodies and thyroglobulin antibodies.ConclusionIodine deficiency, excessive iodine, subclinical hypothyroidism, and positivity for thyroid autoantibodies remain prevalent among women of childbearing age in China. Women of childbearing age who are relatively older, are overweight, or have a family history of thyroid disorders are encouraged to undergo active screening of their UIC and thyroid function when planning a pregnancy.     

High prevalence of TPO-Abs and subclinical hypothyroidism in iodine-sufficient pregnant women in Northern Algeria

BackgroundIodine is a trace element whose adequate intakes are essential during gestation to promote the correct growth and development of the fetus. Historically, endemic goiter and cretinism affected northern regions of Algeria, and iodized salt was introduced in 1990. However, there has been no national study of iodine nutrition in Algeria since 1994. The aim of this study was to assess the iodine status and thyroid function of women of reproductive age (WRA) and pregnant women (PW) in northern Algeria.MethodsHealthy WRA and PW were recruited from an urban area (Algiers) and healthy WRA from a rural area (Tizi-Ouzou). Spot urine and venous blood samples were collected to assess iodine status (urinary iodine concentration, UIC) and serum thyroid hormones (TSH, FT4), thyroglobulin (Tg), and anti-thyroid peroxidase antibodies (TPO-Ab) concentrations.ResultsThe median UIC in WRA was 256 μg/L (IQR: 166−354 μg/L; n = 151) in Algiers and 253 μg/L (167−341 μg/L; n = 150) in Tizi-Ouzou. The median UIC for the PW in Algiers was 233 μg/L (IQR: 157−326 μg/L; n = 173).Thirty-five percent of WRA and 30% of PW had an UIC > 300 μg/L. Median TSH, FT4 and Tg concentrations were within reference ranges in all groups of women. Among PW, 72.7%, 75.4% and 75.5% in the first, second and third trimester were TPO-Ab+. Among TPO-Ab + PW in the first, second and third trimesters, 18.7%, 13% and 10.3% had subclinical hypothyroidism.ConclusionIn northern Algeria, median UICs in PW indicate iodine sufficiency, and in WRA indicate more than adequate intakes. About 75% of PW are TPO-Ab + and the prevalence of subclinical hypothyroidism is high. Monitoring and surveillance of iodine fortification programs is vital to avoid both iodine deficiency and excess. There is an urgent need for a comprehensive national iodine status survey including school-age children and other vulnerable population groups in Algeria.     

Serum Selenium Levels in Patients With Graves Disease With or Without Thyroid Ophthalmopathy

BackgroundGraves disease is one of the most common autoimmune thyroid diseases. Thyroid has the highest concentration of selenium (Se) in the body. Se plays a crucial role in the functioning of some thyroid enzymes; however, there are controversial results regarding the administration of serum Se levels in patients with Graves disease.MethodsIn this study, patients with Graves disease with orbitopathy (GO group) or without orbitopathy (GD group) were recruited. Healthy individuals without a history of any disease were enrolled as the control group. Serum Se and thyroid hormone levels, including T3, T4, and thyroid-stimulating hormone (TSH), were measured using atomic absorption and radioimmunoassay techniques, respectively.ResultsIn this cross-sectional study, 60 and 56 patients and 58 healthy subjects were included in the GO, GD, and control groups. Serum Se levels in the GO, GD, and control groups were 94.53 ± 25.36 μg/dL, 96.82 ± 30.3 μg/dL, and 102.55 ± 16.53 μg/dL, respectively (P = .193). There was a reverse association between the serum Se level and thyroid hormones, including T3, T4, and TSH, in the GO group. However, serum Se levels exhibited a significant reverse association with T4 and TSH hormones but not with T3 in the GD group.ConclusionOur results showed no significant differences in the serum Se levels in the GO and GD groups compared with that in the control group. In addition, we did not detect any significant difference in the serum Se levels between the GO and GD groups.     

Safe Range of Iodine Intake Levels: A Comparative Study of Thyroid Diseases in Three Women Population Cohorts with Slightly Different Iodine Intake Levels

Iodine excess may lead to thyroid diseases. Our previous 5-year prospective survey showed that the prevalence and incidence of hypothyroidism or autoimmune thyroiditis increased with iodine intake. The aim of the present study was to investigate the optimal range of iodine intake by comparing the prevalence of thyroid diseases in three areas with slightly different levels of iodine intake. In 2005, 778 unselected women subjects from three areas with different iodine intake levels were enrolled. Levels of serum thyroid hormones, thyroid autoantibodies, and urinary iodine were measured, and thyroid B ultrasounds were performed. Among the subjects with mildly deficient iodine intake, those with adequate intake, and those with more than adequate intake, the prevalence of clinical and subclinical hypothyroidism was 0, 1.13, and 2.84%, respectively (P = 0.014); that of thyroid goiter was 24.88, 5.65, and 11.37%, respectively (P < 0.001); that of serum thyrotropin values was1.01, 1.25, and 1.39 mIU/l, respectively; and that of serum thyrotropin/thyroglobulin ratio was 7.98, 6.84, and 5.11, respectively (P < 0.001). In conclusion, median urinary iodine 100~200 μg/l may reflect the safe range of iodine intake levels. Serum thyrotropin/thyroglobulin ratio might be a better index of evaluating iodine status.     

Influence of Levothyroxine With Recombinant Human Thyroid-Stimulating Hormone on Urinary Iodine Excretion Before Radioactive Iodine Administration

ObjectiveStimulation with recombinant human thyroid-stimulating hormone (rhTSH) before radioactive iodine administration for patients with thyroid cancer may increase the body iodine pool in the presence of continued levothyroxine; however, the precise significance of its influence remains unclear.MethodsThis was a prospective observational study conducted between March 2017 and August 2020. We measured the 24-hour urinary iodine excretion and urinary iodine-to-creatinine ratio in patients with thyroid cancer stimulated by rhTSH or thyroid hormone withdrawal (THW) before radioactive iodine administration. Oral iodine intake was controlled by a 7-day self-managed low iodine diet, followed by a strict 3-day low iodine diet while in the hospital.ResultsOverall, 343 subjects were included (rhTSH: n = 181; THW: n = 162). The mean levothyroxine dose in the rhTSH group was 115.2 μg daily. The median 24-hour urinary iodine and urinary iodine-to-creatinine ratio in the rhTSH group (71.0 [interquartile range, 57.5-88.0] μg/day and 80.0 [59.0-97.5] μg/gCr, respectively) were significantly higher than those in the THW group (42.0 [30.0-59.0] μg/day and 39.0 [28.0-61.3] μg/gCr, respectively; both P < .001). After propensity score matching by age, sex, body weight, and renal function (rhTSH: n = 106; THW: n = 106), consistent results for both values were observed for both methods. The increase in urinary iodine with the rhTSH method was smaller than the expected value calculated from the amount of levothyroxine.ConclusionUrinary iodine excretion was significantly higher among patients with rhTSH stimulation than those with THW, indicating that the rhTSH method slightly increases the body iodine pool.     

Exploring the role of copper and selenium in the maintenance of normal thyroid function among healthy Koreans

BackgroundSelenium and iodine are trace elements well known to have important roles in the synthesis and metabolism of thyroid hormones. However, the effects of other trace elements on thyroid hormones are still inconclusive. We investigated the association between several trace elements and thyroid hormones.MethodsThe data of 448 subjects who were measured for both, trace elements and TSH/free T4, at the Heath Checkup Center were retrospectively reviewed. The presence of thyroiditis (from thyroid echogenicity) and thyroid nodules were reviewed in the subjects who underwent thyroid ultrasonography.ResultsBlood concentrations of manganese, copper, selenium, and molybdenum were associated with TSH or free T4. After adjusting for age, sex, BMI, smoking, and alcohol consumption, blood copper levels were positively associated with free T4 in both sexes and selenium levels were positively associated with free T4 in women. There was no association between trace elements and thyroiditis. Blood copper concentration had a weak non-linear association with the presence of thyroid nodules.ConclusionsThis study demonstrated that blood concentrations of copper and selenium were significantly associated with free T4 in healthy Korean subjects with sufficient iodine intake suggesting their role in maintaining normal thyroid function.     

Urinary iodine and thyroid function in a population of healthy pregnant women in the North of Spain

BackgroundIodine is an essential trace element for the synthesis of thyroid hormones, which are keys in maternal metabolism during pregnancy as well as in neurological development during fetal and postnatal life. This was a prospective study on iodine status and thyroid function in women during pregnancy in the Basque country to assess whether there was any relationship among maternal urinary iodine, maternal thyroid function and thyrotropin (TSH) in newborns, and to explore any difference in women experiencing miscarriages.MethodsWe analyzed TSH, free T₄ (FT₄), free T₃ (FT₃), thyroid peroxidase antibody (TPO-Ab) titers in serum and urinary iodine concentrations (UIC) in 2104 women in the first trimester of pregnancy and in 1322 of them in their second trimester. We obtained neonatal TSH levels in 1868 cases.ResultsIn the first (T1) and second trimesters (T2), the median UICs were 88.5 μg/L and 140 μg/L, respectively. No relationship was found between UIC and FT₄, or maternal and neonatal TSH. In T1 and T2, 9.7% and 7.5% of women were TPO-Ab positive, respectively. The total miscarriage rate was 10%. The percentage of miscarriages in healthy women was 8.9%, lower than in women with overt hypothyroidism (21.2%; p < 0.001) and than in women with subclinical hypothyroidism (15.6%; p < 0.025). The miscarriage rate was not higher in TPO-Ab-positive women.ConclusionsIn this study most women had iodine deficiency during pregnancy. Neonatal TSH is not correlated with maternal UIC during pregnancy. Pregnant women with hypothyroidism have a higher rate of miscarriages.     

Tg in Adults as a Sensitive Biomarker of Iodine Status: A 5-Year Follow up Population Study in Different Levels of Iodine Intake Regions

This study was to evaluate the usefulness of serum thymoglobulin (Tg) in adults to assess iodine status through a 5-year cohort study which was conducted in three regions with different levels of iodine intake: mild deficiency, more than adequate, and excess, from 1999 to 2004 in China. A total of 3099 subjects over 14 years old with normal serum levels of Tg in 1999 were eligible, of whom 2448 were followed in 2004. Serum levels of thyroid hormones and thyroid autoantibodies as well as urine iodine were measured, and B-mode ultrasonography of the thyroid was performed. A general linear model was performed to determine the determinant factors of serum Tg. Among subjects with mildly deficient iodine intake, those with more than adequate intake, and those with excessive intake, the baseline levels of serum Tg were substantially different (7.5μg/L, 5.9μg/L, and 6.8μg/L respectively, P<0.01), which were associated with age, sex, the rate of positive TgAb, abnormal thyroid volume, abnormal TSH, and positive personal history of thyroid diseases. The data from 1856 subjects with normal range of thyroid parameters but no personal history of thyroid diseases were analyzed to clarify the effect of iodine intake on Tg. Among these three regions, the serum Tg levels were substantially different in both 1999 and 2004, with a similar pattern for increased Tg (ΔTg) (3.1μg/L, 2.5μg/L and 3.5μg/L respectively, P<0.01). The general linear model analysis revealed that age, Tg, and baseline TSH levels were the determinants of ΔTg besides iodine intake. In conclusion, serum Tg in adults, resulting from a time-accumulative effect of iodine exposure, is a useful biomarker of regional iodine intake.     

Thyroid Physiology in Pregnancy

ObjectiveVarious physiological changes occur in maternal thyroid economy during pregnancy. This review focuses on the events taking place during gestation that together strongly influence maternal thyroid function.MethodsScientific reports on maternal thyroid physiology in pregnancy.ResultsDuring the 1^st trimester, human chorionic gonadotropin (hCG) induces a transient increase in free thyroxine (FT4) levels, which is mirrored by a lowering of thyroid-stimulating hormone (TSH) concentrations. Following this period, serum FT4 concentrations decrease of approximately 10 to 15%, and serum TSH values steadily return to normal. Also starting in early gestation, there is a marked increase in serum thyroxine-binding globulin (TBG) concentrations, which peak around midgestation and are maintained thereafter. This event, in turn, is responsible for a significant rise in total T4 and triiodothyronine (T3). Finally, significant modifications in the peripheral metabolism of maternal thyroid hormones occur, due to the expression and activity of placental types 2 and 3 iodothyronine deiodinases (D2 and D3, respectively).ConclusionIn line with these variations, both free thyroid hormone and TSH reference intervals change throughout pregnancy, and most scientific societies now recommend that method-and gestation-specific reference ranges be used for interpreting results in pregnancy.The maternal iodide pool reduces during pregnancy because of increased renal clearance of iodine and transfer of iodine to the feto-placental unit. This results in an additional requirement of iodine during pregnancy of ~ 100% as compared to nonpregnant adults. In accordance, the recommended iodine intake in pregnancy is 250 μg/day. A daily iodine intake below this threshold poses risks of various degrees of thyroid insufficiency for both the mother and the fetus. (Endocr Pract. 2014;20:589-596)     

Iodine Nutrition During Pregnancy in Toronto,Canada

ObjectiveTo evaluate the status of iodine nutrition among pregnant women presenting for routine antenatal care in Toronto, Canada, as determined by the median urine iodine concentration (UIC) of this population.MethodsA cross-sectional, observational study was conducted involving 142 pregnant women recruited from four low-risk antenatal outpatient clinics in Toronto, Canada. Subjects completed a questionnaire and provided a spot urine sample for the measurement of iodine concentration.ResultsMean maternal age was 33.8 ± 4.3 years. Mean gestational age was 29.3 ± 7.8 weeks. The median UIC was 221 μg/L (interquartile range, 142 to 397 μg/L). Six women (4.2%) had urine iodine levels <50 μg/L, and 36 women (25.4%) had levels between 50 and 150 μg/L.ConclusionThis cohort of primarily Caucasian, well-educated, and relatively affluent pregnant women in Toronto, Canada, are iodine sufficient, perhaps due to universal salt iodization and/or other dietary and lifestyle factors. (Endocr Pract. 2013;19:206-211)     

A Stratified Cross-Sectional Cluster Model Survey of Iodine Nutrition in Armenia After A Decade of Universal Salt Iodization

Objective: Iodine is a necessary nutrient for the synthesis of thyroid hormones and essential in human development. Being naturally deficient in iodine, Armenia launched a national universal salt iodization (USI) strategy in 2004. Although high rates of goiter continued to be reported, iodine status has not been studied since 2005. Therefore, this study sought to assess the current situation of population iodine nutrition in Armenia.Methods: We used a selective cross-sectional model to recruit three groups: school-age children (SAC), pregnant women (PW), and nonpregnant women of reproductive age (WRA) from each province. We collected casual urine and table salt samples from each participant, which were analyzed for iodine concentration. A repeat urine sample was collected in a subset of participants to adjust the results for within-person variation in iodine concentration. Group-wise urinary iodine concentrations (UICs) were compared with international reference criteria for iodine status.Results: Urine samples were collected from 1,125 participants from 13 different towns in Armenia; a total of 1,078 participants were included in the final analysis: 361 SAC (mean age, 10.5 years, 46.6% female), 356 PW (mean age, 26.1 years), and 361 WRA (mean age, 35.5 years). Population and geographically weighted median UIC were: SAC, 242 μg/L (&lsqb;25th percentile] 203 to &lsqb;75th percentile] 289 μg/L); PW, 226 μg/L (209 to 247 μg/L); WRA, 311 μg/L (244 to 371 μg/L). A total of 1,041 table salt samples were sufficient for laboratory analysis: 973 (93.4%) of the salt iodine measurements were within the national standard range of 40 ± 15 mg/kg.Conclusion: The results of household salt sampling indicated a successful USI strategy. While the present study did not achieve a truly representative sample of Armenia's population, the UIC results support the conclusion that iodine deficiency has not recurred and is not an underlying factor for any remaining high goiter prevalence in Armenia.Abbreviations: PW = pregnant women; SAC = school-age children; SI = salt iodine; UIC = urinary iodine concentration; USI = universal salt iodization; WHO = World Health Organization; WRA = women of reproductive age     

Iodine status of Turkish pregnant women and their offspring: A national cross-sectional survey

BackgroundThis national cross-sectional survey aimed to assess the iodine status in pregnant women and their offspring, and also to demonstrate regional differences by measuring urinary iodine concentration (UIC). For each woman and her newborn a questionnaire was prepared with basic facts as age, parity number or birth weight and additional information regarding thyroid diseases, use of iodized salt in the household, extra iodine supplementation during pregnancy, education level and wage income.MethodsThe target population represented 1444 pregnant women who gave birth between January 1 st, 2018 and 2019, and their offspring. Iodine deficiency for pregnant women and their offspring were defined as urine iodine level <150 μg/L and <100 μg/L, respectively. Results are given as median (25th–75th percentile).ResultsThe median UIC in the group of pregnant woman was 94 (52–153) μg/L. Within the sample of 1444 pregnant women, UIC indicative of mild iodine deficiency (100−149 μg/L) was present in 21 % (n = 306), moderate deficiency (50−99 μg/L) in 30 % (n = 430), and severe deficiency (<50 μg/L) in 23 % (n = 337). This study showed a prevalence of 74 % of iodine deficiency in Turkish pregnant woman. The median UIC in the group of offspring was 96 (41−191) μg/L. Within the new-borns, UIC indicative of mild iodine deficiency (50−99 μg/L) was present in 22 % (n = 323), moderate deficiency (20−49 μg/L) in 15 % (n = 222), and severe deficiency (<20 μg/L) in 13 % (n = 192). This survey showed a prevalence of 51 % of iodine deficiency in Turkish new-borns. Pregnant women with lower socioeconomic and education level, lower access to household iodized salt, lower rates of exposure to povidone-iodine containing skin disinfectant, higher parity and higher iodine deficiency had higher rates of iodine deficiency in their offspring. Regional differences were observed both in mothers and their offspring concerning their iodine status.ConclusionsOur findings suggest that iodine deficiency is still an important public health problem in Turkey. More drastic measures should be taken to decrease these important iodine deficiencies, both in pregnant women and in their offspring.     

Lead Accumulation as Possible Risk Factor for Primary Open-Angle Glaucoma

The objective of this study was to investigate the relationship between preeclampsia and iodine levels and magnesium concentration in the blood of subjects in the northeast Anatolia region where iodine deficiency is common. Blood specimens were obtained from 24 preeclamptic and 16 healthy pregnant women. Iodine levels in blood were determined by the Foss method based on the Sandell–Kolthoff reaction. Serum protein-bound iodine (PBI) levels and magnesium concentration in maternal blood were lower in patients with severe preeclampsia compared to normal pregnant women (8.46?±?1.22 vs. 11.46?±?1.71 μg/dL, p?<?0.001, 1.63?±?0.05 vs. 1.86?±?0.05 mg/dL, p?<?0.001, respectively). Serum PBI levels and magnesium concentration in umbilical cord blood were higher in patients with severe preeclampsia than in normal pregnant women (8.84?±?1.9 vs. 7.33?±?1.07 μg/dL, p?<?0.05, 2.48?±?0.03 vs. 2.02?±?0.01 mg/dL, p?<?0.001, respectively). There was a positive correlation between the serum PBI levels in maternal blood and magnesium concentration in maternal blood in patients with severe preeclampsia (r?=?0.41, p?<?0.05). Thus, iodine may be one factor contributing to the pathophysiology of preeclampsia. Iodine supplementation may be effective therapy in preeclamptic in pregnant women.     

Geographical and seasonal variation in iodine content of cow’s milk in the UK and consequences for the consumer´s supply

BackgroundDairy products provide a crucial source of dietary iodine for the majority of the UK population, contributing approximately 30–40 % of daily intake. Fluctuations in the iodine content of purchased milk both seasonally and annually implies potential fragility of iodine supply likely through fluctuating supplementation practices in cow herds. We set out to establish the level of national variation in herds and identify factors which might impact milk iodine content.MethodsMilk samples were obtained from 98 herds across the UK via the National Milk Laboratories in August and December 2016. Iodine concentration of samples was measured using ICP-MS. Milk samples and feed intake data were additionally taken from 22 cows from the University of Nottingham (UON) dairy herd.ResultsThere was considerable variation in milk iodine content from < 0.012 (Limit of Detection) to 1558 μg L⁻¹, with a summer median of 197 μg L⁻¹ and winter median 297 μg L⁻¹. Overall, winter values were higher than summer counterparts (P < 0.001) and this held true for samples taken from the North West (P = 0.002) and South West (P = 0.006) but not for other regions studied. Data from the UON herd showed a negative relationship between iodine content and milk yield (P = 0.03) and we found that milk iodine content varied considerably despite apparently similar iodine intakes.ConclusionsRegional differences in milk iodine concentration between summer and winter suggests that feeding practices are far from uniform across the country. The negative association observed between iodine concentration and milk yield in UON samples, suggests that reduced summer values may be influenced by dilution in addition to seasonal differences in concentrate feed provision.     

Serum thyroglobulin as a biomarker of iodine excess and thyroid disease occurrence in adults

BackgroundThyroglobulin (Tg) is considered a sensitive indicator of iodine deficiency. However, the usefulness of Tg as a biomarker of excess iodine is uncertain. The present study aimed to determine the influence of different iodine intake on serum Tg levels, evaluate the influence of thyroid diseases on the distribution of Tg, and identify the factors that may affect Tg levels.MethodsA cross-sectional survey with a total of 1208 adults was conducted in different water iodine areas in China. Urinary iodine concentration (UIC), water iodine concentration (WIC), serum Tg, thyroid-stimulating hormone (TSH), and thyroid antibodies were measured. The thyroid volumes and nodules were measured by B-scan ultrasound.ResultsBased on the WIC data, subjects were divided into three groups. Based on the median urinary iodine concentration (MUIC) data, the iodine levels were adequate, more than adequate, and excess for the WIC < 10 μg/L group, 10 μg/L ≤ WIC ≤ 100 μg/L g, and WIC > 100 μg/L groups, respectively. The median Tg was significantly higher in the excess iodine group than in the adequate iodine group and the more than adequate iodine group (14.6 μg/L vs.12.7 μg/L, P = 0.042; 14.6 μg/L vs.12.5 μg/L, P = 0.004). Multiple linear regression analysis showed that excess iodine intake, goitre, thyroid nodules, and hypothyroidism were significantly related to higher serum Tg levels.ConclusionSerum Tg level can be a promising biomarker of excessive iodine intake, but other factors, especially the presence of thyroid disease, should be considered when using this parameter.     

Excess iodinuria in infants and its relation to the iodine in maternal milk

ObjectiveIodine is an essential micro nutrient, and a deficiency or excessive intake of this mineral is related to changes in thyroid function. In Brazil, both deficiency and excessive intake of iodine are common; however, excessive intakes have recently been observed. Thus, the objective of the present study was to assess the iodine concentration in maternal milk, taking into account the salt iodine concentration of the participating households and in the infants’ urine.MethodUrine samples from 33 infants (less than 6 months of age), maternal milk samples and samples of the kitchen salt used by the mothers were collected. The iodine levels in the urine and maternal milk were assessed by ICP-MS; the iodine levels in the salt were assessed by titration.ResultThe median iodinuria value in the infants was 293 μg/L; the mean iodine concentration was 206 μg/L in the maternal milk and 39.9 mg I/kg in the salt. There was a positive correlation between the iodine concentration in the maternal milk and the infant iodinuria value.ConclusionThe median infant iodinuria was elevated due to the high iodine concentration present in the maternal milk. High iodine values were caused by high salt iodine levels, which should be reduced.     

The role of iodine in human growth and development

Iodine is an essential component of the hormones produced by the thyroid gland. Thyroid hormones, and therefore iodine, are essential for mammalian life. Iodine deficiency is a major public health problem; globally, it is estimated that two billion individuals have an insufficient iodine intake. Although goiter is the most visible sequelae of iodine deficiency, the major impact of hypothyroidism due to iodine deficiency is impaired neurodevelopment, particularly early in life. In the fetal brain, inadequate thyroid hormone impairs myelination, cell migration, differentiation and maturation. Moderate-to-severe iodine deficiency during pregnancy increases rates of spontaneous abortion, reduces birth weight, and increases infant mortality. Offspring of deficient mothers are at high risk for cognitive disability, with cretinism being the most severe manifestation. It remains unclear if development of the offspring is affected by mild maternal iodine deficiency. Moderate-to-severe iodine deficiency during childhood reduces somatic growth. Correction of mild-to-moderate iodine deficiency in primary school aged children improves cognitive and motor function. Iodine prophylaxis of deficient populations with periodic monitoring is an extremely cost effective approach to reduce the substantial adverse effects of iodine deficiency throughout the life cycle.     

Role of Bamboo-Shoot in the Pathogenesis of Endemic Goiter in Manipur,North East India

ObjectiveEndemic goiter is prevalent in the iodine-sufficient region of Manipur, India. Bamboo shoot (BS), a goitrogenic plant food, are consumed regularly in the area. The objective of this study was to examine the role of BS in the pathogenesis of endemic goiter.MethodsGoiter prevalence, urinary iodine, and thiocyanate (SCN) excretion in school children, iodine content in drinking water, and the household consumption of salt fortified with iodine were measured. To confirm the goitrogenic potential of BS, its progoitrogenic constituents were fed to rats as part of an iodine-sufficient diet, after which the animals' thyroid gland morphology and functional status were assessed.ResultsGoiter prevalence was 31% in 4852 children, and the median urinary I and SCN levels were 176.3 μg/L and 0.962 ± 0.190 mg/dL, respectively. Of the households assessed, 90% consumed salt fortified with adequate iodine. Progoitrogenic constituents were high in BS from Manipur. Increased thyroid weight, hypertrophy and hyperplasia of follicular cells, decreased thyroid peroxidase activity, and low serum thyroxine (T₄) and triiodothyronine (T₃) levels were observed in BS-fed rats.ConclusionNearly one third of the studied participants had palpable goiter, despite a successful salt iodine fortification program. SCN from BS causes goiter in iodine-sufficient experimental animals. Similar ingestion in study participants was confirmed and is the likely cause for the persistence of endemic goiter in the Manipur region. (Endocr Pract. 2013;19:36-45)