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.

Urinary iodine excretion and individual iodine supplementation among elderly subjects: A cross-sectional investigation in the commune of Randers, Denmark

1995 ◽  
Vol 132 (2) ◽  
pp. 171-174 ◽  
Author(s):  
Klaus M Pedersen ◽  
Eigil Iversen ◽  
Peter Laurberg
Keyword(s):  
Urinary Iodine ◽  
Cross Sectional Study ◽  
Iodine Intake ◽  
Elderly Subjects ◽  
Urinary Iodine Excretion ◽  
Sectional Study ◽  
Cross Sectional ◽  
Iodine Supplementation ◽  
Median Level ◽  
Iodine Excretion

Pedersen KM, Iversen E, Laurberg P. Urinary iodine excretion and individual iodine supplementation among elderly subjects. A cross-sectional investigation in the commune of Randers, Denmark. Eur J Endocrinol 1995;132:171–4. ISSN 0804–4643 Several studies have demonstrated that the iodine intake is relatively low in Denmark. However, the results are difficult to interpret because no information has been given on the frequency of individual iodine supplementation. We performed a cross-sectional study of elderly subjects living in the commune of Randers, Denmark. Urinary iodine excretion was measured in the 423 participants (185 males, 238 females) and a careful history was taken on any possible intake of supplementary iodine. The median urinary iodine excretion was 48.3 μg/g creatinine for the whole population (40.8 μg/g creatinine in males, 53.2 μg/g creatinine in females). In the part of the population that did not take iodine supplementation (46.7%) the median value was 36.1 μg/g creatinine (males 33.8; females 38.8). Regular iodine supplementation taken as an iodine-containing vitamin/mineral tablet was found in 30.8% of the population. This increased the urinary iodine excretion to a median level of 80.5 μg/g creatinine (males 62.0; females 88.0). The study shows that the basic iodine intake level is overestimated if individual iodine supplementation is not taken into account. Such supplementation may lead to median iodine excretion values that seem reasonable, even if the iodine intake of the part of the population not taking iodine (in this study, nearly half of the population) is low. Klaus Pedersen, Department of Internal Medicine and Endocrinology, Aalborg Hospital, Reberbansgade, DK-9000 Aalborg, Denmark

scholarly journals Evaluation of iodine nutritional status during pregnancy by estimated 24-hour urinary iodine excretion: population variation range and individual accuracy

2021 ◽  
pp. 1-22
Author(s):  
Ye Bu ◽  
Yan Cai ◽  
Chunlei Ji ◽  
Chunyan Zhao ◽  
Chunyuan Tian ◽  
...  
Keyword(s):  
Nutritional Status ◽  
Pregnant Women ◽  
Urinary Iodine ◽  
Reference Interval ◽  
Iodine Intake ◽  
Urinary Iodine Excretion ◽  
Individual Level ◽  
Excessive Iodine ◽  
Iodine Excretion ◽  
The Individual

Abstract Objective: To explore the accuracy of estimated 24-hour urinary iodine excretion(24hUIEest) in assessing iodine nutritional status. Design: Fasting venous blood, 24-hour and spot urine samples were collected during the day. The urinary iodine concentration (UIC) and urinary creatinine concentration (UCrC) were measured, and the urinary iodine-to-creatinine ratio (UI/Cr), 24hUIEest, and 24-hour urinary iodine excretion(24hUIE) were calculated. At the population level, correlation and consistency between UIC, UI/Cr, 24hUIEest and 24hUIE were assessed using correlation analysis and Bland-Altman plots. At the individual level, ROC curves were used to analyse the accuracy of the above indicators for evaluating insufficient and excessive iodine intake. The reference interval of 24hUIEest was established based on percentile values. Setting: Indicator can accurately evaluate individual iodine nutrition during pregnancy remains controversial. Participants: Pregnant women (n=788). Results: Using 24hUIE as standard, the correlation coefficients of 24hUIEest from different periods of the day ranged from 0.409 to 0.531, and the relative average differences ranged from 4.4% to 10.9%. For diagnosis of insufficient iodine intake, the area under the ROC curve of 24hUIEest was 0.754, sensitivity and specificity were 79.6% and 65.4%, respectively. For diagnosis of excessive iodine intake, the area of 24hUIEest was 0.771, sensitivity and specificity were 66.7% and 82.0%, respectively. The reference interval of 24hUIEest was 58.43-597.65μg. Conclusions: 24hUIEest can better indicate iodine nutritional status at a relatively large sample size in a given population of pregnant women. It can be used for early screening at the individual level to obtain more lead time for pregnant women.

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 Excess dietary iodine intake in long-term African refugees

2006 ◽  
Vol 9 (1) ◽  
pp. 35-39 ◽  
Author(s):  
Andrew J Seal ◽  
Paul I Creeke ◽  
Daniella Gnat ◽  
Fathia Abdalla ◽  
Zahra Mirghani
Keyword(s):  
Urinary Iodine ◽  
Iodine Intake ◽  
Humanitarian Assistance ◽  
World Health ◽  
Urinary Iodine Excretion ◽  
Urinary Iodine Concentration ◽  
Cross Sectional ◽  
Excessive Iodine ◽  
Iodine Excretion

AbstractObjectiveTo assess the iodine status of long-term refugees dependent on international food aid and humanitarian assistance.DesignA series of cross-sectional two-stage cluster or systematic random sample surveys which assessed urinary iodine excretion and the prevalence of visible goitre. Salt samples were also collected and tested for iodine content by titration.SettingSix refugee camps in East, North and Southern Africa.SubjectsMale and female adolescents aged 10–19 years.Main resultsThe median urinary iodine concentration (UIC) ranged from 254 to 1200 μg l−1 and in five of the camps exceeded the recommended maximum limit of 300 μg l−1, indicating excessive iodine intake. Visible goitre was assessed in four surveys where it ranged from 0.0 to 7.1%. The camp with the highest UIC also had the highest prevalence of visible goitre. The iodine concentrations in 11 salt samples from three camps were measured by titration and six of these exceeded the production-level concentration of 20 to 40 ppm recommended by the World Health Organization (WHO), but were all less than 100 ppm.ConclusionsExcessive consumption of iodine is occurring in most of the surveyed populations. Urgent revision of the level of salt iodisation is required to meet current WHO recommendations. However, the full cause of excessive iodine excretion remains unknown and further investigation is required urgently to identify the cause, assess any health impact and identify remedial action.

scholarly journals Epidemiological survey on the relationship between different iodine intakes and the prevalence of hyperthyroidism

2002 ◽  
pp. 613-618 ◽  
Author(s):  
F Yang ◽  
W Teng ◽  
Z Shan ◽  
H Guan ◽  
Y Li ◽  
...  
Keyword(s):  
Iodine Deficiency ◽  
Urinary Iodine ◽  
Iodine Intake ◽  
Urinary Iodine Excretion ◽  
Subclinical Hyperthyroidism ◽  
Cross Sectional ◽  
Iodine Excess ◽  
Salt Iodization ◽  
Iodine Excretion ◽  
The Impact

OBJECTIVE: To investigate the effect of different levels of iodine intake on the prevalence of hyperthyroidism and the impact of universal salt iodization on the incidence of hyperthyroidism. DESIGN: A comparative cross-sectional and longitudinal survey was conducted in three areas with borderline iodine deficiency, mild iodine excess (previously mild iodine deficiency) and severe iodine excess. Universal salt iodization had been introduced 3 years previously except in the area with borderline iodine deficiency. METHODS: In total 16 287 inhabitants from three areas answered a questionnaire concerning the history of thyroid disease. Among them 3761 unselected subjects received further investigations including thyroid function, thyroid autoantibodies, thyroid ultrasonography and urinary iodine excretion. RESULTS: Among areas with median urinary iodine excretion of 103 microg/l, 375 microg/l and 615 microg/l (P<0.05), the prevalence of hyperthyroidism did not differ significantly (1.6%, 2% and 1.2%). The prevalence of subclinical hyperthyroidism was higher in areas with borderline iodine deficiency and mild iodine excess than in the area with severe excess iodine intake (3.7%, 3.9% and 1.1%, P<0.001). The prevalence of Graves' disease and its proportion in hyperthyroidism did not differ among areas. The incidence of hyperthyroidism did not significantly increase after the introduction of universal salt iodization. CONCLUSION: Different iodine intakes under a certain range do not affect the prevalence and type of hyperthyroidism. Subclinical hyperthyroidism is more prevalent in the iodine deficient area than in the severe iodine excessive area. In the area with mild iodine deficiency, the introduction of universal salt iodization may not be accompanied by an increased incidence of hyperthyroidism.

Earliest prevention of endemic goiter by iodine supplementation during pregnancy

1996 ◽  
Vol 134 (4) ◽  
pp. 443-448 ◽  
Author(s):  
Klaus Peter Liesenkötter ◽  
Wolfgang Göpel ◽  
Ulrich Bogner ◽  
Barbara Stach ◽  
Annette Grüters
Keyword(s):  
Thyroid Function ◽  
Iodine Deficiency ◽  
Endemic Goiter ◽  
Urinary Iodine ◽  
Thyroid Volume ◽  
Urinary Iodine Excretion ◽  
Thyroid Peroxidase ◽  
Iodine Supplementation ◽  
Iodine Excretion ◽  
Maternal Thyroid

Liesenkötter KP, Göpel W, Bogner U, Stach B, Grüters A. Earliest prevention of endemic goiter by iodine supplementation during pregnancy. Eur J Endocrinol 1996;134:443–8. ISSN 0804–4643 During pregnancy complex changes of maternal thyroid function occur and they are influenced by the maternal iodine supply. It has been demonstrated that with decreasing iodine supply maternal goiter and hypothyroxinemia as well as fetal and neonatal hypothyroidism become more prevalent. Therefore iodine supplementation during pregnancy is now strongly recommended also in areas of moderate iodine deficiency. To monitor the success of iodine supplementation and its theoretical risk of increasing the frequency of thyroid autoantibodies, we have investigated the thyroid volume, thyroid function, urinary iodine excretion and antibodies to thyroid peroxidase at 10–12 weeks of gestation and postpartum in 38 mothers receiving 300 μg potassium iodide/day and in 70 mothers without iodine supplementation. In all of their newborns thyroid volume was determined by ultrasound. The thyrotropin (TSH) levels and antibodies to thyroid peroxidase (TPO-ab) in the neonates were measured in dried blood spots on filter paper from their newborn screening. Urinary iodine excretion was increased significantly after iodine supplementation in mothers (p < 0.001) and their newborns (<0.05). No hypo- or hyperthyroidism was observed in the mothers or newborns. Interestingly, no difference of maternal thyroid volumes was observed between the two groups after pregnancy, but the volumes of the thyroid glands in newborns of mothers who received iodine were significantly (p < 0.004) lower (0.7 ± 0.4 ml) than in the control group (1.5 ± 1.1 ml). There was no change in the frequency of TPO-ab in either group after pregnancy. In four mothers transplacental passage of these antibodies was documented by positive measurement in the blood sample of the newborn. This study documents that iodine supplementation during pregnancy in an area of moderate iodine deficiency results in a lower size of neonatal thyroid volume and that this supplementation was not accompanied by an increase in the frequency of TPO-ab. Klaus Peter Liesenkötter, Kinderklinik Kaiserin Auguste Victoria Haus (KAVH), Virchow-Klinikum der Medizinische Fakultät der Humboldt-Universität zu Berlin, Heubnerweg 6, 14059 Berlin, Germany

scholarly journals Nationwide Representative Survey of Dietary Iodine Intake and Urinary Excretion in Postpartum Korean Women

Nutrients ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 3955
Author(s):  
Do-Kyung Lee ◽  
Hunjoo Lee ◽  
Hyeyoung Lee ◽  
Taehyung Yoon ◽  
Seon-Joo Park ◽  
...  
Keyword(s):  
Large Scale ◽  
Urinary Iodine ◽  
Brown Seaweed ◽  
Nationwide Survey ◽  
Iodine Intake ◽  
Urinary Iodine Excretion ◽  
Korean Women ◽  
Spot Urine ◽  
Before And After ◽  
Iodine Excretion

Iodine is an essential component of thyroid hormones, but excessive iodine intake can lead to thyroid dysfunction. Traditionally, Korean mothers consume brown seaweed soup (miyeokguk), a high source of iodine, after childbirth. There is controversy regarding the effects of excessive postpartum iodine intake on the health of mothers and infants. Thus far, there have been no nationwide large-scale surveys regarding the status of iodine intake among postpartum women in Korea. Therefore, we conducted a nationwide survey of postpartum dietary iodine intake among Korean women. In total, 1054 Korean women aged ≥19 years, at less than 8 weeks postpartum, participated in this survey. Dietary data were collected using self-reported 2-day dietary records, along with before-and-after meal photos. To evaluate the correlation between dietary iodine and urinary iodine excretion (UIE), spot urine, and 24 h urine samples were collected from 98 and 29 participants, respectively. The mean daily iodine intake among all participants was 2945.6 μg, and it gradually decreased over time after childbirth. Dietary iodine intake was significantly correlated with 24 h UIE (r = 0.396, p < 0.05) and spot urine UIE (r = 0.312, p < 0.05). Follow-up studies are required to examine the influence of excessive postpartum iodine intake on thyroid health in mothers and their infants.

Iodine and Goiter in Children

PEDIATRICS ◽  
1975 ◽  
Vol 56 (1) ◽  
pp. 82-90
Author(s):  
Frederick L. Trowbridge ◽  
Josip Matovinovic ◽  
Gordon D. McLaren ◽  
Milton Z. Nichaman
Keyword(s):  
United States ◽  
Urinary Iodine ◽  
The United States ◽  
Iodine Intake ◽  
Urinary Iodine Excretion ◽  
High Iodine ◽  
Goiter Prevalence ◽  
Iodine Excretion ◽  
American Children

Goiter examination was performed on 7,785 children aged 9 to 16 years in four areas of the United States—Michigan, Kentucky, Texas, and Georgia. Urinary iodine and creatinine, thyroxine, protein-bound iodine, and plasma inorganic iodide determinations were made on 377 matched pairs of goitrous and nongoitrous control children. The overall prevalence of goiter was 6.8%. Most children with goiter had palpably but not visibly enlarged thyroids and showed no evidence of clinical or biochemical thyroid abnormality. Mean urinary iodine excretion was 452µg/gm of creatinine, many times the 50µg/gm of creatinine level used to define deficiency. Children with goiter and areas with high goiter prevalence tended to have higher rather than lower iodine excretion. These findings are consistent with other data indicating high iodine intakes in the United States and suggest that goiter in American children cannot be assumed to be related to iodine deficiency. The possible role of high iodine intake in the causation of goiter is discussed.

scholarly journals Iodine bioavailability from cow milk: a randomized, crossover balance study in healthy iodine-replete adults

2019 ◽  
Vol 110 (1) ◽  
pp. 102-110 ◽  
Author(s):  
Olivia L van der Reijden ◽  
Valeria Galetti ◽  
Sarah Bürki ◽  
Christophe Zeder ◽  
Adam Krzystek ◽  
...  
Keyword(s):  
Urinary Iodine ◽  
Iodine Intake ◽  
Cow Milk ◽  
Urinary Iodine Excretion ◽  
High Concentration ◽  
Total Iodine ◽  
Balance Study ◽  
Iodine Absorption ◽  
Iodine Excretion ◽  
Potential Matrix

ABSTRACTBackgroundMilk and dairy products are considered important dietary sources of iodine in many countries. However, to our knowledge, iodine bioavailability from milk has not been directly measured in humans.ObjectiveThe aim of this study was to compare iodine bioavailability in iodine-replete adults from: 1) cow milk containing a high concentration of native iodine; 2) milk containing a low concentration of native iodine, with the addition of potassium iodide (KI) to assess a potential matrix effect; and 3) an aqueous solution of KI as a comparator; with all 3 containing equal amounts of total iodine (263 µg/250 mL). We also speciated iodine in milk.DesignWe conducted a 3-wk, randomized, crossover balance study in adults (n = 12) consuming directly analyzed, standardized diets. During the 3 test conditions — high intrinsic iodine milk (IIM), extrinsically added iodine in milk (EIM), and aqueous iodine solution (AIS) — subjects collected 24-h urine over 3 d and consumed the test drink on the second day, with 3- or 4-d wash-out periods prior to each treatment. Iodine absorption was calculated as the ratio of urinary iodine excretion (UIE) to total iodine intake. Milk iodine speciation was performed using ion chromatography-mass spectrometry.ResultsIodine intake from the standardized diet was 195 ± 6 µg/d for males and 107 ± 6 µg/d for females; the test drinks provided an additional 263 µg. Eleven subjects completed the protocol. There was a linear relation between iodine intake and UIE (β = 0.89, SE = 0.04, P < 0.001). There were no significant differences in UIE among the 3 conditions (P = 0.24). Median (range) fractional iodine absorption across the 3 conditions was 91 (51–145), 72 (48–95), and 98 (51–143)% on days 1, 2, and 3, respectively, with day 2 significantly lower compared with days 1 and 3 (P < 0.001). In milk, 80–93% of the total iodine was inorganic iodide.ConclusionNearly all of the iodine in cow milk is iodide and although fractional iodine absorption from milk decreases with increasing dose, its bioavailability is high. The trial was registered at clinicaltrials.gov as NCT03590431.

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