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 ([25th percentile] 203 to [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 Deficiency and Excess in Children: Worldwide Status in 2013

ObjectiveAssessing iodine nutrition at the population level is usually done by measuring the urinary iodine concentration (UIC) and, in some countries, by estimating household coverage of adequately iodized salt (HHIS). Using these indicators, the objective of this review is to assess global and national iodine status in 2013.MethodsThe most recent data on HHIS were obtained from the United Nations Children's Fund. The most recent data on UICs were obtained from the International Council for the Control of Iodine Deficiency Disorders Global Network and the World Health Organization (WHO). Median UIC was used to classify national iodine status based on the current WHO classification system, with the following modification: the “adequate (100 to 199 μg/L)” and “more than adequate (200 to 299 μg/L)” categories of median UIC in school-aged children were combined into a single category of “adequate” iodine intake (100 to 299 μg/L).ResultsOver the past decade, the number of countries that are iodine deficient has fallen from 54 to 30. The number iodine-sufficient countries has increased from 67 to 112, while the number with excessive iodine intake has increased from 5 to 10. In most countries with excess intake, this is due to overiodization of salt and/or poor monitoring of salt iodization. Out of 128 countries with HHIS data, at least 90% of households in 37 countries consume adequately iodized salt, but in 39 countries, coverage rates are below 50%. Overall, about 70% of households worldwide have access to iodized salt.ConclusionThere has been substantial recent progress in the global effort to control iodine deficiency. However, iodized salt programs need to be carefully monitored to ensure adequate iodine intake while avoiding iodine excess. (Endocr Pract. 2013;19:839-846)     

Influence of Bisphenol A on Thyroid Volume and Structure Independent of Iodine in School Children

Background

Although several studies have evaluated the relationship between bisphenol A (BPA) and thyroid functions, their results are not entirely consistent. Little is known about BPA in relation to thyroid volume and structure.

Methods

We examined the association of BPA with thyroid volume and thyroid nodules using data from 718 Chinese children living in the East Coast of China in 2012. First morning urine samples were collected for the determination of urinary BPA, creatinine, and urinary iodine concentrations (UIC). Thyroid volume (TV) and nodules were assessed by thyroid ultrasonography.

Results

The median of TV was 3.14ml. 459(63.9%) children took iodized salt at home and the median of UIC was 159μg/l. BPA was detected in 99.9% of the urine samples and the medians for boys and girls were 2.64 and 2.35μg/g creatinine, respectively. Of all participants 14.0% had thyroid nodules. Urinary BPA concentration was inversely associated with thyroid volume (β = -0.033, 95% CI: -0.053, -0.013) and the risk for multiple nodules (OR = 0.78; 95% CI: 0.63, 0.97). The associations above were similar for children who consumed iodized salt and those consumed non-iodized salt.

Conclusions

The data suggest that BPA may be one of the influencing factors for TV and thyroid nodules and its effects are independent of iodine nutrition status in children.     

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.     

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 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 < .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: 230 μg/L) than those who took less (median: 191 μg/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 190 μg/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.     

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 Comparison of Iodine Status in Children and Pregnant Women After a Policy Change in the Iodized Salt Standard in Shanghai,China

In Shanghai, a new iodized salt standard was implemented in 2012. To provide evidence to the government, we compared iodine status before (35 mg/kg) and after (30 mg/kg) adjustment in vulnerable populations living in Shanghai. The probability-proportional-to-size sampling technique was used to select at least 360 pregnant women for urine iodine test and at least 1200 students for thyroid measurement and the household salt test. Of these students, at least 360 performed urine iodine test. The median thyroid volume and the median household salt iodine concentration of children aged 8–10 years were 1.80 ml and 24.8 mg/kg in 2015, and 0.97 ml and 28.3 mg/kg in 2011. The median urine iodine concentration (UIC) of pregnant women was 126.52 and 139.77 μg/L in 2015 and 2011. All differences were statistically significant (P?<?0.05). The median UIC of students was 171.40 and 181.63 μg/L in 2015 and 2011, the difference was not statistically significant. Multivariate linear regression analysis showed that thyroid volume in children was associated with sex, age, region, and household salt iodized concentration. The current iodized salt concentration meets the basic needs of the population’s iodine requirements except for pregnant women. Periodic monitoring is necessary particularly in vulnerable groups.     

Urinary Iodine Concentration is Inversely Associated with Thyroglobulin Antibodies

Objective: Epidemiologic studies on the relationship between iodine and thyroid antibodies are inconsistent. Iodine nutrition, genetic, and environmental factors have been shown to modify the effects of iodine on thyroid autoimmunity. We investigated the relationship between urinary iodine concentration (UIC) and thyroglobulin antibodies (TgAbs) in individuals living in iodine-sufficient areas in this cross-sectional study.Methods: A total of 15,008 participants were recruited according to the age range of the population of China in our study. An oral questionnaire was administered to collect basic demographic information. Serum thyrotropin (TSH), thyroid peroxidase antibodies (TPOAbs), TgAbs, and UIC were measured, and thyroid ultrasonography was performed in all subjects. Participants were further divided according to the level of UIC and the status of TgAb, and logistic regression was applied to determine the relationship between UIC and TgAbs.Results: The median UIC of the study population was 205.23 (95% confidence interval &lsqb;CI], 65.7 to 537.67) μg/L. A total of 17.6% of participants had UIC <100 μg/L. With the increase in UIC, the prevalence of positive TgAbs decreased gradually. UIC level was lowest in subjects with high TgAb titer (median, 182.36 μg/L; 95% CI, 52.88 μg/L to 506.71 μg/L) and highest in the TgAb-negative group (median, 207.16 μg/L; 95% CI, 66.94 μg/L to 538.72 μg/L). Multilinear correlation analysis showed that gender (β = 37.632; P<.001), age (β = 0.467; P = .038), TSH (β = 13.107; P<.001), TPOAb (β = 1.150; P<.001), thyroid volume (β = 2.883; P<.001), and UIC (β = -0.047; P = .032) were independent predictors of TgAb variations. Low UIC (<100 μg/L) was associated with increased risk of positive TgAbs (adjusted odds ratio = 1.255 &lsqb;1.004 to 1.568]).Conclusion: Low UIC is an independent risk factor for positive TgAb in individuals living in iodine-sufficient areas.Abbreviations: CI = confidence interval; CV = coefficient of variation; FT3 = free triiodothyronine; FT4 = free thyroxine; OR = odds ratio; TgAb = thyroglobulin antibody; TPOAb = thyroid peroxidase antibody; TSH = thyrotropin; UIC = urinary iodine concentration; USI = universal salt iodization     

Urinary iodine and sodium concentration and thyroid status in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

ObjectivesTo evaluate urinary iodine concentration (UIC) in civil servants aged 35-74 years of the Brazilian Study of Adults Health (ELSA-Brasil) to analyze its relationship with sociodemographic, clinical risk factors, lifestyle, urinary Na and thyroid status.DesignCross-sectional study in six Brazilian cities.MethodsThis analysis included 792 participants with information about urinary iodine concentration (UIC). Thyroid status was defined by serum levels of TSH/FT4 and the current use of antithyroid drugs for treatment of overt hyperthyroidism or levothyroxine to treat overt hypothyroidism. The determination of UIC was carried out with an inductively coupled plasma mass spectrometer (ICP-MS) and was expressed as median with Interquartile Range (IQR).ResultsIn 792 participants, thereof 52% women, mean age was 51.9 (9.0) years. The median UIC was 219 (IQR, 166-291) for all persons studied, thereof 211 (IQR, 157-276) for women and 231 (IQR, 178-304) for men. According to the WHO classification, for all persons studied, 60% had more than adequate iodine-supply (UIC ≥200 μg/L), 37% were adequately supplied (UIC 100-199 μg/L) and <3% had a deficient iodine status (<100 μg/L). In the 35-44-year age strata, which includes women of childbearing age, 23.2% of women presented less than 150 μg/L of UIC. No differences in UIC were detected according to thyroid status. (P = 0.39) The correlation between Ur-Na and UIC showed a Spearman coefficient of 0.52 (P < 0.0001) and it was also found an association of Ur-Na with UIC: Beta of 1.76 (95% Confidence Interval (95% CI): 1.01 to 2.51. The urinary Na concentration showed a synergy with the UIC, that means medians of 57, 72, 107 and 141 mmol Na/L urine (P < 0.001) in the groups with the four UIC classes according to the WHO grading mentioned above. The very low Na content in the persons exhibiting <100 μg/L UIC seems to reflect also a higher urine volume due to the frequent use of diuretics. The strong relationship between the urinary Na concentration and the UIC points to a dependence of the UIC on the individual consumption of iodized salt, which should be more considered in future studies. The strong relationship between the urinary Na concentration and the UIC points to a dependence of the UIC on the individual consumption of iodized salt, which should be more considered in future studies.ConclusionsEuthyroid persons were dominating by more than four fifths and no significant association was found between UIC and thyroid status. Although most of the persons studied present more than adequate iodine intake it was observed that nearly a quarter of women in childbearing age are iodine deficient.     

The Association of Thyroid Nodule with Non-Iodized Salt among Chinese Children

Objective

The controversy that iodized salt may increase the risk of thyroid disorders has been aroused in China during the past decade. Most of studies focused on adult rather than children. We aimed to explore whether iodized salt was associated with an increased risk of thyroid nodule in Chinese children.

Methods

The cross-sectional study was conducted in Hangzhou, China, in 2010. Iodized salt intake, urine iodine concentration (UIC) and thyroid nodule (by ultrasonography) were measured in 3026 children. The associations of iodized salt with thyroid nodule were evaluated using multiple logistic regression models.

Results

The prevalence of thyroid nodule was 10.59% among Chinese children. Girls (11.89%) had higher prevalence of thyroid nodule than boys (9.26%). No significant association was observed between type of salt and thyroid nodule in pooled samples, boys and girls, respectively. Similar associations were observed between UIC and thyroid nodule. There was no significant association between milk consumption and thyroid nodule as well.

Conclusion

The present study indicated that non-iodized salt may not increase the risk of thyroid nodules among Chinese children. Similar associations were observed between milk consumption, UIC and thyroid nodules.     

Goiter prevalence,serum selenium,and urine iodine status in a previously iodine-deficient area in Turkey

This study was planned to investigate goiter prevalence and serum selenium and urine iodine status among school-age children in the Ankara region of Turkey. Nine hundred five (905) children were investigated; 847 of them were included in the study. Thyroid ultrasound was performed on children who were suspected of being goitrous at physical examination. Serum TSH, thyroxine, triiodotyronine, thyroid antibody, and urine iodine concentrations (UIC) are also measured. Ultrasound measurements revealed a goiter in 107 (12.6%) of the 847 children. Goiter prevalence was significantly lower among iodized-salt users compared to the noniodized salt using group. UIC and serum selenium levels in the goitrous group were significantly lower compared to the nongoitrous group. Despite legally enforced table salt iodization, the region shows the characteristics of mild iodine deficiency. In addition to lower UIC, goitrous children have lower serum selenium levels compared to the nongoitrous ones. Thus, selenium deficiency plays an important role in goiter endemics in Turkey. It can be postulated that table salt iodization might not be enough for the preventive measures of goiter, but informing people about the correct ways of iodized salt consumption, enforcing the iodization of industrial salts, and, as important as these measures, taking selenium deficiency into consideration are essential for preventing goiters in endemic areas.     

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)     

Assessing iodine intakes in pregnancy and strategies for improvement

An adequate intake of iodine in the diet of pregnant women is important to ensure normal growth and development of the fetus. It is difficult, however, to accurately determine iodine intakes using traditional methods of dietary assessment, primarily because the contribution of iodised salt use, at the table and in cooking, to total iodine intake is difficult to quantify. Given the limitations of dietary assessment, biochemical indices in blood and urine are typically used to assess iodine status in children and adults. Although reference ranges exist for thyroid hormones, there has been no consensus on the cut-offs needed in pregnancy to diagnose iodine deficiency. In contrast, a median urinary iodine concentration (UIC) of 150-249 μg/L has been established to determine the adequate iodine status of a group of pregnant women. However, the large intra-individual variation in UIC from either spot or 24h urine samples means that UIC cannot be used to assess iodine status in an individual pregnant woman. The difficulty in determining if an individual pregnant woman is iodine deficient is problematic for cross-sectional studies examining associations between iodine status in pregnancy and developmental outcomes in the child.     

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.     

Iodized oil as a complement to iodized salt in schoolchildren in endemic goiter in Romania

OBJECTIVE: To evaluate the long-term efficacy and possible side effects of low doses of iodized oil on iodine nutrition and thyroid function in endemic goiter in Romania. METHODS: Random selection of 214 schoolchildren aged 6-14 years. Serial measurements of urinary iodine, thyroid volume with ultrasound, serum concentrations of thyrotropin, free thyroxine, thyroglobulin and thyroid autoantibodies before and up to 2 years after the oral administration of 200 mg iodine in iodized oil. RESULTS: Urinary iodine concentrations indicated a moderate iodine deficiency before therapy, sharply increased soon after therapy and slowly decreased thereafter but remained within the normal range up to more than 1 year after therapy. The prevalence of goiter was 29% before the administration of iodized oil and 9% 1 year later. Thyroid function tests and autoantibodies were normal before and up to 2 years after therapy. CONCLUSION: A single dose of 200 mg iodine from oral Lipiodol appears adequate and safe for correcting moderate iodine deficiency in children.     

Iodine Deficiency and Excess Coexist in China and Induce Thyroid Dysfunction and Disease: A Cross-Sectional Study

Background

In spite of the salt iodization, iodine deficiency disorders (IDD) have not been sustainably eliminated in China. There are coastal areas with low iodized salt coverage rates (iodine nutrition is inadequate) and other areas with excessive amounts of iodine in the drinking water.

Objective

This study aimed to clarify the association of iodine deficiencies resulting from a low coverage rate of iodized salt, excess iodine intake from drinking water with thyroid function and disease in adults.

Design

A cross-sectional study was conducted in adults in different iodine nutrition areas in three provinces in China.

Results

The prevalence of thyroid nodules was 15.52%, 8.66% and 22.17% in the iodine excess, sufficient and deficient groups, respectively. The prevalence of subclinical hypothyroidism was 20.09%, 10.41%, and 2.25% in the excess, sufficient and deficient iodine groups, respectively. The prevalence of subclinical hyperthyroidism and overt hyperthyroidism in the iodine deficient group was higher than that in the iodine excess group ( = 9.302, p = 0.002) and iodine sufficient group ( = 7.553, p = 0.006). Thyroid-stimulating hormone (TSH) was significantly correlated with excess iodine intake (β = 1.764,P = 0.001) and deficient iodine intake (β = −1.219, P = 0.028).

Conclusions

Thyroid nodules are more likely to be present in the iodine excess and deficient areas than in the iodine sufficient areas. Subclinical hyperthyroidism and overt hyperthyroidism are more likely to be prevalent in the iodine deficient areas than in the iodine excess or sufficient areas. Subclinical hypothyroidism is more likely to be prevalent in the high iodine intake areas than in the iodine deficient or sufficient areas. Median TSH may be deemed as an alternative indicator for monitoring the iodine nutrition status of the adult population in iodine excess and deficient areas.     

Evaluación de los hábitos alimentarios relacionados con la ingesta de yodo,el estado nutricional de yodo y disfunción tiroidea en cuatro poblaciones no seleccionadas (proyecto Tirobus)

IntroductionMost of the studies on urinary iodine levels in Spain in the last decade have reported a significant improvement. A survey was undertaken together with an information campaign on the thyroid gland, the importance of iodine intake and hypothyroidism in four Spanish cities. The goals of the survey were to obtain information on consumption of iodine-containing foods, to measure urinary iodine levels and to evaluate the prevalence of thyroid dysfunction.Materials and methodsA non-preselected population attending the information campaign centers located in Barcelona, La Coruña, Malaga and Madrid was studied. A questionnaire on fish, milk and iodized salt consumption was administered. Urinary iodine levels (Pino's method) and thyrotropin (TSH) concentrations (Whatman 903^® dry paper method) were measured.ResultsA total of 872 questionnaires were completed (Madrid 40%; La Coruña 27%; Malaga 19%; and Barcelona 14%). The mean age was 51 years (SD 16); 81% were women. A total of 60.6% of interviewees reported they consumed iodized salt, 90.8% reported daily milk intake and 29.3% reported fish consumption ≥3 times per week. The mean urinary iodine concentration was 143.2 μg/L. The prevalence of high TSH levels (>4 mUI/L) was 1.3% and that of low TSH levels (<0.4 mUI/mL) was 1.2%.ConclusionsAccording to the World Health Organization criteria, the median urinary iodine concentration, both overall or by city, is indicative of optimal iodine intake. In addition to iodized salt intake, consumption of products such as milk and fish has probably contributed to these positive results. The prevalences of undiagnosed hyperthyroidism and hypothyroidism detected in this study were similar to those found in other studies.     

Preliminary investigation on iodine nutrition in captive giant pandas

Background/ObjectiveThe giant panda belongs to the family Ursidae and, as a species of bear, still retains the simple digestive system of a Carnivoran. However, under the pressure of a specific habitat they had to adapt to a plant mono-diet consisting of bamboo with different species and growth stages around the year. A plant-based diet has relatively low iodine content with risk of iodine deficiency. Furthermore, bamboo contains cyanogenic glycosides releasing cyanide whose detoxification metabolite the thiocyanate acts as antagonist against iodine uptake and storage in the thyroid. To date very little is known about the iodine nutritional status of the giant panda, thus this study was conducted to receive the first information about the iodine nutrition of captive giant panda.Subjects/MethodsHere we investigated the iodine content of bamboo with different plant parts/vegetation stage and species and further compounds of the captive giant panda diet. Next, the urinary iodine (UI) and urinary thiocyanate (UT) levels of infant, sub-adult, adult and geriatric captive giant pandas was measured during the periods when the pandas consume both bamboo leaves- and culm (bamboo leaf-culm stage). Afterwards, the UI of 19 adult giant pandas was measured again for the different iodine intake during bamboo shoot stage. Finally, in this study part also the fecal iodine concentration was analyzed for calculation of total iodine excretion in relation to the iodine intake.ResultsBamboo leaves had the highest iodine content (453 μg/kg dry matter (DM)), followed by the shoots (84 μg/kg DM, p < 0.05), while bamboo culm had the lowest value (12 μg/kg DM, p < 0.05). During bamboo leaf-culm stage, giant pandas of different age groups had different UI and UT levels (p < 0.05). Furthermore, UI and UT were positively correlated among sub-adult, adult and geriatric giant pandas (p < 0.05). In adult giant pandas during bamboo shoot stage, the iodine excretion in feces was not different from that in urine while their total iodine excretion was less than their iodine intake (p < 0.05). Moreover, during bamboo shoot stage, the UI level of adult giant pandas was much lower than noted during bamboo leaf-culm stage (p < 0.05).ConclusionsOur results indicate that UI of captive giant pandas was related to their age as well as to the vegetation stage/part of bamboo they consumed reflecting a different periodic iodine supply. Thiocyanate and fecal excretion should be emphasized when considering the iodine nutrition of giant pandas.     

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.