scholarly journals Thyroid and the environment: exposure to excessive nutritional iodine increases the prevalence of thyroid disorders in São Paulo, Brazil

2008 ◽  
Vol 159 (3) ◽  
pp. 293-299 ◽  
Author(s):  
Rosalinda Y A Camargo ◽  
Eduardo K Tomimori ◽  
Solange C Neves ◽  
Ileana G S Rubio ◽  
Ana Luiza Galrão ◽  
...  
Keyword(s):  
Urinary Iodine ◽  
Iodine Intake ◽  
Sao Paulo ◽  
Thyroid Peroxidase ◽  
Urinary Iodine Concentration ◽  
São Paulo ◽  
Table Salt ◽  
Excessive Iodine ◽  
Salt Iodine ◽  
Excessive Iodine Intake

ObjectiveTo evaluate the prevalence of chronic autoimmune thyroiditis (CAT) and iodine-induced hypothyroidism, hyperthyroidism (overt and subclinical), and goiter in a population exposed to excessive iodine intake for 5 years (table salt iodine concentrations: 40–100 mg/kg salt).DesignThis was a population-based, cross-sectional study with 1085 participants randomly selected from a metropolitan area in São Paulo, Brazil, and conducted during the first semester of 2004.MethodsThyroid ultrasound examination was performed in all participants and samples of urine and blood were collected from each subject. Serum levels of thyroid-stimulating hormone, free thyroxine, and anti-thyroid peroxidase (TPO) antibodies, urinary iodine concentration, thyroid volume, and thyroid echogenicity were evaluated. We also analyzed table salt iodine concentrations.ResultsAt the time the study was conducted, table salt iodine concentrations were within the new official limits (20–60 mg/kg salt). Nevertheless, in 45.6% of the participants, urinary iodine excretion was excessive (above 300 μg/l) and, in 14.1%, it was higher than 400 μg/l. The prevalence of CAT (including atrophic thyroiditis) was 16.9% (183/1085), women were more affected than men (21.5 vs 9.1% respectively, P=0.02). Hypothyroidism was detected in 8.0% (87/1085) of the population with CAT. Hyperthyroidism was diagnosed in 3.3% of the individuals (36/1085) and goiter was identified in 3.1% (34/1085).ConclusionsFive years of excessive iodine intake by the Brazilian population may have increased the prevalence of CAT and hypothyroidism in subjects genetically predisposed to thyroid autoimmune diseases. Appropriate screening for early detection of thyroid dysfunction may be considered during excessive nutritional iodine intake.

scholarly journals Chronic iodine excess does not increase the incidence of hyperthyroidism: a prospective community-based epidemiological survey in China

2007 ◽  
Vol 156 (4) ◽  
pp. 403-408 ◽  
Author(s):  
Fan Yang ◽  
Zhongyan Shan ◽  
Xiaochun Teng ◽  
Yushu Li ◽  
Haixia Guan ◽  
...  
Keyword(s):  
Urinary Iodine ◽  
Iodine Intake ◽  
Urinary Iodine Excretion ◽  
Thyroid Peroxidase ◽  
Community Based ◽  
Iodine Excess ◽  
Iodine Supplementation ◽  
Excessive Iodine ◽  
Iodine Excretion ◽  
Excessive Iodine Intake

Objective: An increasing incidence of hyperthyroidism has been observed when iodine supplementation has been introduced to an iodine-deficient population. Moreover, the influence of chronic more than adequate or excessive iodine intake on the epidemiological features of hyperthyroidism has not been widely and thoroughly described. To investigate the influences of different iodine intake levels on the incidence of hyperthyroidism, we conducted a prospective community-based survey in three communities with mild-deficient, more than adequate (previously mild deficient iodine intake), and excessive iodine intake. Subjects and methods: In three rural Chinese communities, a total of 3761 unselected inhabitants aged above 13 years participated in the original investigation and 3018 of them received identical examinations after 5 years. Thyroid function, levels of thyroid peroxidase antibody (TPOAb), thyroglobulin antibody and urinary iodine excretion were measured and thyroid ultrasound examination was also performed. Results: In three communities, median urinary iodine excretion was 88, 214, and 634 μg/l (P<0.05) respectively. The cumulative incidence of hyperthyroidism was 1.4, 0.9, and 0.8% (P>0.05) respectively. Autoimmune hyperthyroidism was predominant in thyroid hyperfunction in all the three cohorts. Either positive TPOAb (>50 U/ml) or goiter in original healthy participants was associated with the occurrence of unsuspected hyperthyroidism in 5 years (logistic regression, OR=4.2 (95% CI 1.7–8.8) for positive TPOAb, OR=3.1 (95% CI 1.4–6.8) for goiter). Conclusion: Iodine supplementation may not induce an increase in hyperthyroidism in a previously mildly iodine-deficient population. Chronic iodine excess does not apparently increase the risk of autoimmune hyperthyroidism, suggesting that excessive iodine intake may not be an environmental factor involved in the occurrence of autoimmune hyperthyroidism.

scholarly journals The prevalence of thyroid dysfunction in elderly cardiology patients with mild excessive iodine intake in the urban area of São Paulo

Clinics ◽  
2009 ◽  
Vol 64 (2) ◽  
pp. 135-142 ◽  
Author(s):  
Glaucia C. Duarte ◽  
Eduardo K. Tomimori ◽  
Rosalinda Y. A. Camargo ◽  
Ileana G.S. Rubio ◽  
Mauricio Wajngarten ◽  
...  
Keyword(s):  
Urban Area ◽  
Thyroid Dysfunction ◽  
Iodine Intake ◽  
Sao Paulo ◽  
São Paulo ◽  
Excessive Iodine ◽  
Excessive Iodine Intake

scholarly journals Urinary iodine concentration: a biochemical parameter for assessing the iodine status

Mediscope ◽  
2018 ◽  
Vol 5 (2) ◽  
pp. 30-35
Author(s):  
GM Molla
Keyword(s):  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Iodine Concentration ◽  
Iodine Intake ◽  
Urinary Iodine Concentration ◽  
Lactating Women ◽  
Iodine Status ◽  
Excessive Iodine ◽  
Pregnancy And Lactation ◽  
Neonates And Infants

Iodine is a micronutrient, which is essential for the synthesis of thyroid hormones. Thyroid hormones play a major role in the development of different functional components in different stages of life. The relationship between iodine intake level of a population and occurrences of thyroid disorders U-shaped with an increase from both low and high iodine intake. Iodine deficiency disorders (IDDs) are a major health problem worldwide in all age groups, but infants, school children, and pregnant and lactating women are vulnerable. During pregnancy and lactation, the fetus and infants are sensitive to maternal iodine intake. Even mild iodine deficiency may lead to irreversible brain damage during this period. A main cause of IDDs of neonates and infants is maternal iodine deficiency. Universal salt iodization strategy has been initiated by the World Health Organization and United Nation International Children Emergency Fund by the year 1993 for correction and prevention of iodine deficiency. Excessive iodine causes hypothyroidism, iodine-induced hyperthyroidism and autoimmune thyroid diseases. Iodine deficiency and excessive iodine, both cause goiter. There are many indicators for assessing the IDDs, such as measurement of thyroid size by palpation or ultrasonography, serum thyroid stimulating hormone, and thyroglobulin but these are less sensitive, costly and sometimes interpretation is difficult. Urinary iodine concentration (UIC) is a well-accepted, cost-efficient, and easily obtainable indicator of iodine status. Since the majority of iodine absorbed by the body is excreted in the urine, it is considered a sensitive marker of current iodine intake and can reflect recent changes in iodine status. Iodine requirements are greatly increased during pregnancy and lactation, owing to metabolic changes. During intrauterine life, maternal iodine is the only source of iodine for a fetus. UIC determines the iodine status of pregnant and lactating women. Breast milk is the only source of iodine for exclusively breastfed neonates and infants. Breast milk iodine concentration can be determined by UIC. UIC predicts the adverse health consequences of excessive iodine intake such as goiter, hypothyroidism, and hyperthyroidism. This review presents that iodine status in different groups of a population can be determined by UIC which will be helpful in assessing the iodine status in a community, finding out the cause of thyroid disorders, to predict the risk of adverse health effects of iodine deficiency and excessive iodine, and in making plan for iodine supplementation.Mediscope Vol. 5, No. 2: Jul 2018, Page 30-35

scholarly journals An epidemiological survey of children's iodine nutrition and goitre status in regions with mildly excessive iodine in drinking water in Hebei Province, China

2012 ◽  
Vol 15 (7) ◽  
pp. 1168-1173 ◽  
Author(s):  
Shengmin Lv ◽  
Jun Zhao ◽  
Dong Xu ◽  
Zhengshui Chong ◽  
Lihui Jia ◽  
...  
Keyword(s):  
Drinking Water ◽  
Urinary Iodine ◽  
Thyroid Volume ◽  
Iodine Concentration ◽  
Hebei Province ◽  
Systematic Sampling ◽  
Urinary Iodine Concentration ◽  
Iodine Nutrition ◽  
Excessive Iodine ◽  
Salt Iodine

AbstractObjectiveTo identify children's iodine nutrition and goitre status in areas with mildly excessive iodine in drinking water.DesignA cross-sectional survey. Probability proportional to size sampling was employed to randomly select children from thirty townships where the median iodine content in drinking water ranged from 150 to 300 μg/l; their urinary iodine concentrations were determined and their thyroid volumes were measured by ultrasound. Drinking water samples and salt samples from the villages where the children lived were collected using a systematic sampling method.SettingHebei Province of China.SubjectsA total of 1259 children aged 8–10 years (621 boys and 638 girls).ResultsChildren's median urinary iodine concentration was found to be 418·8 μg/l, and the iodine concentration was >300 μg/l for 68·3 % (248/363) of the urine samples. Children's median urinary iodine concentration in villages with median salt iodine >10 mg/kg was significantly higher than that in villages with median salt iodine <5 mg/kg (442·9 μg/l v. 305·4 μg/l, P ≈ 0). The goitre rate of 1259 children examined by ultrasound was 10·96 %.ConclusionsThe iodine intake of children living in areas with mildly excessive iodine in drinking water in Hebei Province was found to be excessive. The measured iodine excess in the sampled children is exacerbated by consumption of iodized salt. Goitre was identified in these areas; however, due to the limitation of the current criteria for children's thyroid volume, a comprehensive assessment of the prevalence of goitre in these regions could not be made and further study is required.

scholarly journals Iodine Status and Thyroid Function in a Group of Seaweed Consumers in Norway

Nutrients ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3483
Author(s):  
Inger Aakre ◽  
Lidunn Tveito Evensen ◽  
Marian Kjellevold ◽  
Lisbeth Dahl ◽  
Sigrun Henjum ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Urinary Iodine ◽  
Iodine Content ◽  
Iodine Concentration ◽  
Iodine Intake ◽  
Thyroid Stimulating Hormone ◽  
Urinary Iodine Concentration ◽  
Free Triiodothyronine ◽  
Iodine Status ◽  
Excessive Iodine

Seaweeds, or macroalgae, may be a good dietary iodine source but also a source of excessive iodine intake. The main aim in this study was to describe the iodine status and thyroid function in a group of macroalgae consumers. Two urine samples were collected from each participant (n = 44) to measure urinary iodine concentration (UIC) after habitual consumption of seaweed. Serum thyroid stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), and peroxidase autoantibody (TPOAb), were measured in a subgroup (n = 19). A food frequency questionnaire and an iodine-specific 24 h recall were used to assess iodine intake and macroalgae consumption. The median (p25–p75) UIC was 1200 (370–2850) μg/L. Median (p25–p75) estimated dietary iodine intake, excluding macroalgae, was 110 (78–680) μg/day, indicating that seaweed was the major contributor to the iodine intake. TSH levels were within the reference values, but higher than in other comparable population groups. One third of the participants used seaweeds daily, and sugar kelp, winged kelp, dulse and laver were the most common species. Labelling of iodine content was lacking for a large share of the products consumed. This study found excessive iodine status in macroalgae consumers after intake of dietary seaweeds. Including macroalgae in the diet may give excessive iodine exposure, and consumers should be made aware of the risk associated with inclusion of macroalgae in their diet.

scholarly journals Association between Urinary Iodine Concentration and Thyroid Nodules in Adults: A Cross-Sectional Study in China

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Hui Sun ◽  
Hanyu Wang ◽  
Xiaolan Lian ◽  
Chao Liu ◽  
Bingyin Shi ◽  
...  
Keyword(s):  
Thyroid Nodules ◽  
Urinary Iodine ◽  
Iodine Concentration ◽  
Cross Sectional Study ◽  
Iodine Intake ◽  
Thyroid Peroxidase ◽  
Urinary Iodine Concentration ◽  
Cross Sectional ◽  
Physical Examinations ◽  
The Relationship

Background. Associations between iodine intake and thyroid nodules (TNs) were not consistent. We aimed to illustrate the relationship between urinary iodine concentration (UIC) and TNs. Methods. A total of 12,698 participants were enrolled in analysis. All of the participants filled out questionnaires and underwent physical examinations, laboratory tests, and thyroid ultrasonography. UIC, serum thyrotropin (TSH), thyroid peroxidase antibodies (TPOAb), and thyroglobulin antibodies (TgAb) were measured in the central laboratory. Results. The prevalence of TNs was 16.00%, and the median UIC was 206.1 μg/L. TNs and UIC were negatively related when UIC was less than 527 μg/L ( adjusted   OR = 0.87 ; 95% CI, 0.80, 0.94), and the relationship between UIC and TNs was not statistically significant when UIC was greater than 527 μg/L ( adjusted   OR = 1.25 ; 95% CI, 0.98, 1.60). In women, UIC was negatively associated with risk for TNs (adjusted OR 0.95; 95% CI, 0.91, 0.99). Conclusion. The relationship between TNs and UIC differed between men and women. The risk of TNs decreased with the elevation of UIC in men when UIC was lower than 527 μg/L, while UIC and the presence of TNs were negatively correlated in women. In the future, cohort studies or other studies that can explain causality must be conducted to explore the relationship between iodine status and TNs.

scholarly journals Excessive Iodine Intake Does Not Increase the Recurrence Rate of Graves' Disease after Withdrawal of the Antithyroid Drug in an Iodine-Replete Area

2015 ◽  
Vol 4 (1) ◽  
pp. 36-42 ◽  
Author(s):  
Sun Mi Park ◽  
Yoon Young Cho ◽  
Ji Young Joung ◽  
Seo Young Sohn ◽  
Sun Wook Kim ◽  
...  
Keyword(s):  
Treatment Group ◽  
Clinical Outcomes ◽  
Iodine Intake ◽  
Antithyroid Drugs ◽  
Graves Disease ◽  
Urinary Iodine Concentration ◽  
Repeated Treatment ◽  
Excessive Iodine ◽  
Significant Difference ◽  
Excessive Iodine Intake

Background and Objectives: The relationship between iodine intake and effects of antithyroid drugs (ATD) for Graves' disease, especially in iodine-deficient areas, has been demonstrated in many studies. However, it was not clear how chronic high iodine intake influenced the effectiveness of ATD in an iodine-replete area. This study aimed to clarify the effect of iodine intake on clinical outcomes of Graves' disease after discontinuation of ATD in Korea, an iodine-replete area. Methods: A total of 142 patients with Graves' disease who visited the outpatient clinic regularly and stopped their ATD between October 2011 and April 2013 were enrolled in our study. Urinary iodine concentration (UIC) was measured just before and after the discontinuation of ATD. Results: Median UIC was not significantly different between the remission and relapse groups, as well as among the four treatment groups (group 1, remission after initial treatment; group 2, remission after repeated treatment; group 3, early relapse within a year; group 4, late relapse after a year). Remission rates did not show a significant difference between the excessive iodine intake (UIC ≥300 μg/l) and average iodine intake groups (UIC <300 μg/l). Conclusions: The present study suggests that excessive iodine intake does not have an effect on the clinical outcomes of Graves' disease in an iodine-replete area, and therefore diet control with iodine restriction might not be necessary in the management of Graves' disease.

scholarly journals Iodine insufficiency in pregnant women from the State of São Paulo

2014 ◽  
Vol 58 (3) ◽  
pp. 282-287 ◽  
Author(s):  
Sabrina Maria Saueia Ferreira ◽  
Anderson Marliere Navarro ◽  
Patrícia Künzle Ribeiro Magalhães ◽  
Léa Maria Zanini Maciel
Keyword(s):  
Pregnant Women ◽  
Urinary Iodine ◽  
Sao Paulo ◽  
The State ◽  
World Health ◽  
Nutrition Status ◽  
Urinary Iodine Concentration ◽  
São Paulo ◽  
Iodine Nutrition ◽  
Iodine Supply

Objective : The intake of adequate amounts of iodine during pregnancy is essential for the neurological development of the fetus. The aim of this study was to assess iodine nutrition status in pregnant women from the state of São Paulo, Brazil.Material and methods : We analyzed urinary iodine concentration (UIC) in 191 pregnant and 58 non-pregnant women matched by age. We used the World Health Organization criteria to define sufficient iodine supply (median UIC: 150-249 µg/L among pregnant women, and 100-199 µg/L for non-pregnant women).Results : Median UIC of the pregnant women studied was lower than the recommended value (median = 137.7 µg/L, 95% CI = 132.9 – 155.9), while non-pregnant women had UIC levels within the appropriate range (median = 190 μg/L; 95% IC = 159.3-200.1). UIC was below 150 µg/L in 57% of the pregnant women.Conclusions : Although a larger sample is needed to consolidate these findings, these results raise concerns about the adequacy of the iodine supply of pregnant women in Brazil, especially considering the new determinations of the Brazilian government, which have recently reduced the concentrations of iodine in table salt to 15-45 mg/kg of salt. Arq Bras Endocrinol Metab. 2014;58(3):282-7

scholarly journals Longitudinal trends in thyroid function in relation to iodine intake: ongoing changes of thyroid function despite adequate current iodine status

2014 ◽  
Vol 170 (1) ◽  
pp. 49-54 ◽  
Author(s):  
Annenienke C van de Ven ◽  
Romana T Netea-Maier ◽  
H Alec Ross ◽  
Teun A E van Herwaarden ◽  
Suzanne Holewijn ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Iodine Intake ◽  
Thyroid Peroxidase ◽  
Urinary Iodine Concentration ◽  
Creatinine Concentration ◽  
Iodine Status ◽  
The Past ◽  
Urine Iodine

ObjectiveSeveral cross-sectional studies on populations with iodine deficiency showed that TSH-levels are negatively associated with age, while in populations with high iodine intake TSH is positively associated with age. The question is whether such an age-thyroid function relation is an ongoing process apparent also in longitudinal studies and whether it reflects an actual iodine deficiency or an iodine insufficiency in the past.MethodsIn an area with a borderline iodine status in the past, we studied 980 participants of the Nijmegen Biomedical Study. We measured serum TSH, free thyroxine (FT4), total triiodothyronine (T3), peroxidase antibodies, and the urine iodine and creatinine concentration 4 years after our initial survey of thyroid function, in which we reported a negative association between TSH and age.ResultsWithin 4 years, TSH decreased by 5.4% (95% CI 2.5–8.3%) and FT4increased by 3.7% (95% CI 2.9–4.6%). Median urinary iodine concentration was 130 μg/l. Estimated 24-h iodine excretion was not associated with TSH, T3, change of TSH, or FT4over time or with the presence of antibodies against thyroid peroxidase. Only FT4appeared to be somewhat higher at lower urine iodine levels: a 1.01% (95% CI 0.17–1.84%) higher FT4for each lower iodine quintile.ConclusionsIn this longitudinal study, we found an ongoing decrease in TSH and increase in FT4in a previously iodine insufficient population, despite the adequate iodine status at present. This suggests that low iodine intake at young age leads to thyroid autonomy (and a tendency to hyperthyroidism) that persists despite normal iodine intake later in life.

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