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Eriksson J, Barregard L, Sallsten G, Berlinger B, Weinbruch S, Manousou S, Ellingsen DG, Nyström HF. Urinary iodine excretion and optimal time point for sampling when estimating 24-h urinary iodine. Br J Nutr 2023; 130:1289-1297. [PMID: 36744548 PMCID: PMC10511680 DOI: 10.1017/s0007114523000326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 01/10/2023] [Accepted: 01/30/2023] [Indexed: 02/07/2023]
Abstract
Iodine deficiency may cause thyroid dysfunction. The iodine intake in a population is measured by urinary iodine concentration (UIC) in spot samples or 24-h urinary iodine excretion (24UIE). 24UIE is considered the gold standard and may be estimated using an equation including UIC, urinary creatinine concentration, sex and age (e24UIE). The aims of this study were to evaluate the preferable timing of UIC when using this equation and assess the variability of UIE. Sixty healthy non-smoking women (n 31) and men (n 29) were included in Gothenburg, Sweden. Twelve urine samples were collected at six fixed times on two separate days. Variability was calculated for UIC, 24UIE, e24UIE, iodine excretion per hour (iHr) and UIC adjusted for creatinine and specific gravity. Median 24UIE was 156 µg/24 h and the median UIC (all spot samples) was 104 µg/l. UIC (P < 0·001), 24UIE (P = 0·001) and e24UIE (P < 0·001) were significantly higher in men. e24UIE was relatively similar to 24UIE. However, when e24UIE was calculated from UIC in the first void, it was about 15 % lower than 24UIE (P < 0·001). iHr was lowest in the morning and highest in the afternoon. Median iHr was higher in men (7·4 v. 5·3 µg/h, P < 0·001). The variability of UIE was higher within individuals than between individuals. This study suggests that most time points for estimation of individual 24UIE are appropriate, but they should preferably not be collected in the first void.
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Affiliation(s)
- Janna Eriksson
- Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Praktikertjänst AB, Skövde, 54130, Sweden
| | - Lars Barregard
- Occupational and Environmental Medicine, Department of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Gerd Sallsten
- Occupational and Environmental Medicine, Department of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Balazs Berlinger
- National Institute of Occupational Health, Oslo, Norway
- Department of Animal Hygiene, Herd Health and Mobile Clinic, University of Veterinary Medicine, Budapest, Hungary
| | - Stephan Weinbruch
- National Institute of Occupational Health, Oslo, Norway
- Institute of Applied Geosciences, Darmstadt Technical University, Darmstadt, Germany
| | - Sofia Manousou
- Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Frölunda Specialist Hospital, Västra Frölunda, Sweden
| | | | - Helena Filipsson Nyström
- Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Department of Endocrinology, Institute of Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden
- Wallenberg’s Centre for Molecular and Translational Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden
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Manousou S, Stål M, Eggertsen R, Hoppe M, Hulthén L, Filipsson Nyström H. Correlations of water iodine concentration to earlier goitre frequency in Sweden-an iodine sufficient country with long-term iodination of table salt. Environ Health Prev Med 2019; 24:73. [PMID: 31810448 PMCID: PMC6898976 DOI: 10.1186/s12199-019-0821-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 09/25/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Before iodination of Swedish table salt in 1936, iodine deficiency resulting in goitre and hypothyroidism was common. Sweden has become iodine sufficient, as shown in a national survey in 2007, proving its iodination fortification programme effective for the general population. The objective of this study was to collect drinking water from water treatment plants nationally and test if water iodine concentration (WIC) correlated to urinary iodine concentration (UIC) of school-aged children in a national survey 2007 to former goitre frequency in 1929 and to thyroid volume data in 2007. METHODS In 2012, 166 treatment plants, located in 57% (166 of 290) of all Swedish municipalities, were asked to collect drinking water samples of approximately 10 ml. In 2007, tap water samples of the same volume were collected from 30 randomly selected schools for the national survey. Analysis of WIC was done in both treatment plants in 2012 (n = 166) and tap water in 2007 (n = 30). The correlation of WIC to the children's UIC and thyroid volume after iodination was tested based on data from the national survey in 2007. The association of WIC to former goitre frequency was tested based on pre-iodination data, derived from a map of goitre frequency drawn in 1929. RESULTS The median WIC from water treatment plants was 4.0 μg/L (range 0-27 μg/L). WIC was similar in coastal and inland areas, for both ground and surface water. WIC correlated with historical goitre areas and was lower in the goitre areas than in non-goitre areas (p < 0.001). WIC in the same municipalities as the schools correlated with the UIC of children (p < 0.01), but not with their thyroid volume. CONCLUSIONS WIC still contributes to iodine nutrition in Sweden, but iodination overrides the goitre effect.
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Affiliation(s)
- Sofia Manousou
- Sahlgrenska Academy, Institute of Medicine, University of Gothenburg, Göteborg, Sweden
| | - Maja Stål
- Department of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
| | - Robert Eggertsen
- Sahlgrenska Academy, Institute of Medicine, University of Gothenburg, Göteborg, Sweden. .,School of Public Health and Community Medicine, General Medicine, University of Gothenburg, Göteborg, Sweden.
| | - Michael Hoppe
- Department of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
| | - Lena Hulthén
- Department of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
| | - Helena Filipsson Nyström
- Sahlgrenska Academy, Institute of Medicine, University of Gothenburg, Göteborg, Sweden.,Deparment of Endocrinology, Sahlgrenska University Hospital, Göteborg, Sweden
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Wang Z, Su X, Liu P, Liu S. Dynamic Changes in the Bivariable Distribution of Urinary Iodine Concentration and Thyroid Volume in Children Aged 8 to 10 Years in China. Asia Pac J Public Health 2017; 29:288-295. [DOI: 10.1177/1010539517709027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
National iodine-deficiency disorder surveillance surveys were conducted in 1999, 2005, and 2011 in China. Probability-proportional-to-size sampling technique was used to select sampling units. The mean of thyroid volume (Tvol) in the 100 to 199 µg/L UIC (urinary iodine concentration) group was significantly lower than that in the 200 to 299 µg/L UIC group in 2011 ( P < .05). The status in the 100 to 199 µg/L versus ≥300 µg/L and 200 to 299 µg/L versus ≥300 µg/L groups in 1999, and 100 to 199 µg/L versus ≥300 µg/L group in 2011 were the same ( P < .05). The mean Tvol in the <100 µg/L UIC group was significantly higher than that in the 100 to 199 µg/L UIC group in 1999 ( P < .05). Both insufficient and excess iodine may be associated with an increase in Tvol, and adequate iodine intake should be defined as median UIC 100 to 299 µg/L.
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Affiliation(s)
| | - Xiaohui Su
- Harbin Medical University, Harbin, HL, China
| | - Peng Liu
- Harbin Medical University, Harbin, HL, China
| | - Shoujun Liu
- Harbin Medical University, Harbin, HL, China
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4
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Nyström HF, Brantsæter AL, Erlund I, Gunnarsdottir I, Hulthén L, Laurberg P, Mattisson I, Rasmussen LB, Virtanen S, Meltzer HM. Iodine status in the Nordic countries - past and present. Food Nutr Res 2016; 60:31969. [PMID: 27283870 PMCID: PMC4901513 DOI: 10.3402/fnr.v60.31969] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 05/08/2016] [Accepted: 05/09/2016] [Indexed: 11/19/2022] Open
Abstract
Background Adequate iodine nutrition is dependent on ground water content, seafood, and, as many countries use iodized cow fodder, dairy products. In most countries, salt fortification programs are needed to assure adequate iodine intake. Objectives The objectives are threefold: 1) to describe the past and present iodine situation in the Nordic countries, 2) to identify important gaps of knowledge, and 3) to highlight differences among the Nordic countries’ iodine biomonitoring and fortification policies. Design Historical data are compared with the current situation. The Nordic countries’ strategies to achieve recommended intake and urine iodine levels and their respective success rates are evaluated. Results In the past, the iodine situation ranged from excellent in Iceland to widespread goiter and cretinism in large areas of Sweden. The situation was less severe in Norway and Finland. According to a 1960 World Health Organization (WHO) report, there were then no observations of iodine deficiency in Denmark. In Sweden and Finland, the fortification of table salt was introduced 50–75 years ago, and in Norway and Finland, the fortification of cow fodder starting in the 1950s helped improve the population's iodine status due to the high intake of milk. In Denmark, iodine has been added to household salt and salt in bread for the past 15 years. The Nordic countries differ with regard to regulations and degree of governmental involvement. There are indications that pregnant and lactating women, the two most vulnerable groups, are mildly deficient in iodine in several of the Nordic countries. Conclusion The Nordic countries employ different strategies to attain adequate iodine nutrition. The situation is not optimal and is in need of re-evaluation. Iodine researchers, Nordic national food administrations, and Nordic governmental institutions would benefit from collaboration to attain a broader approach and guarantee good iodine health for all.
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Affiliation(s)
- Helena Filipsson Nyström
- Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Department of Endocrinology, Sahlgrenska University Hospital, Gothenburg, Sweden;
| | | | - Iris Erlund
- National Institute for Health and Welfare, Helsinki, Finland
| | - Ingibjörg Gunnarsdottir
- Unit for Nutrition Research, University of Iceland and Landspitali National University Hospital, Reykjavik, Iceland
| | - Lena Hulthén
- Department of Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Peter Laurberg
- Department of Endocrinology, Aalborg University Hospital, Aalborg, Denmark.,Department of Clinical Medicine, Aalborg University, Aalborg, Denmark
| | | | - Lone Banke Rasmussen
- Department of Endocrinology, Bispebjerg University Hospital, Copenhagen, Denmark
| | - Suvi Virtanen
- National Institute for Health and Welfare, Helsinki, Finland.,School of Health Sciences, University of Tampere, Finland
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Abstract
More than one tenth of the world population is to some degree affected by goitre and most of these harbour nodules. The large differences in thyroid disease prevalence between populations may be caused by genetic and environmental factors. Among the latter, iodine deficiency seems by far to be the most important risk factor. Thus, nodular goitre is a condition predominantly seen in iodine deficient areas of the world. In the present review, we evaluated in detail autopsy and ultrasound studies of the thyroid gland. In autopsy studies, large thyroid volumes and high frequencies of goitres have been reported in countries affected by iodine deficiency. Many cross-sectional studies using thyroid ultrasound investigations have been performed world-wide and reported high thyroid volumes and goitre prevalences, and to some extent also high prevalences of thyroid nodules in iodine-deficient countries. Most of these goitres were classified as nodular goitres. On the other hand, few studies have shown that abundant iodine intake may lead to development of diffuse goitres, but world-wide this has been a minor problem compared with development of nodular goitres. In the past century we have observed a trend towards smaller thyroid glands, and hopefully less than 10% of the world population will experience goitre within a few decades.
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Affiliation(s)
- Allan Carlé
- Department of Endocrinology, Aalborg University Hospital, Hobrovej 18-22, DK-9000 Aalborg, Denmark.
| | - Anne Krejbjerg
- Department of Endocrinology, Aalborg University Hospital, Hobrovej 18-22, DK-9000 Aalborg, Denmark
| | - Peter Laurberg
- Department of Endocrinology, Aalborg University Hospital, Hobrovej 18-22, DK-9000 Aalborg, Denmark
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Nyström HF, Jansson S, Berg G. Incidence rate and clinical features of hyperthyroidism in a long-term iodine sufficient area of Sweden (Gothenburg) 2003-2005. Clin Endocrinol (Oxf) 2013; 78:768-76. [PMID: 23421407 DOI: 10.1111/cen.12060] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 08/13/2012] [Accepted: 09/23/2012] [Indexed: 01/12/2023]
Abstract
OBJECTIVES To study hyperthyroidism in long-term iodine sufficiency (IS), as iodine supply affects its occurrence. DESIGN Prospective descriptive study. PATIENTS In 2003-2005, all referred cases of subclinical (SH) and overt hyperthyroidism (OH) were registered at diagnosis from a population (n = 631 239) in Gothenburg, Sweden. MEASUREMENTS Information on age, gender, smoking, thyroid associated ophthalmopathy (TAO), thyroid hormones and TSH receptor antibodies (TRab) was collected. Incidences were calculated. SH and OH cases with Graves' disease (GD), toxic multinodular goiter (TMNG) and solitary toxic adenoma (STA) were compared. In GD, TRab+ and TRab- cases and patients with (TAO+) and without TAO (TAO-) were compared. RESULTS The total incidence (n/100 000/year) of hyperthyroidism was 27·6; OH 23·8; SH 3·8; GD 21·4; TMNG 4·3; and STA 1·8. SH was more common among TMNG (40·2%) and STA (45·7%) than in GD (5·9%). SH-GD patients were older, more often smokers and had lower TRab levels than OH-GD patients. FreeT4 and T3 levels in GD were higher than in TMNG and STA. FreeT4, T3 and TRab decreased with age in patients with GD, P < 0·0001. TRab- patients had lower T3 than TRab+ patients, P < 0·001. TRab was positively correlated to FreeT4, P < 0·0001. TAO occurred in 20% of patients with GD. TAO+ patients were younger than TAO- patients. Smokers did not have more TAO. CONCLUSION The total incidence of hyperthyroidism was low. GD dominated with an age-related decline of thyroid hormones and TRab levels. The spectrum of hyperthyroidism in this long-term IS area may represent the future situation for countries with shorter history of IS.
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Affiliation(s)
- Helena Filipsson Nyström
- Thyroid Unit, Department of Endocrinology, Sahlgrenska University Hospital, Gröna Stråket 8, Göteborg, Sweden.
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7
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Gunnarsdottir I, Dahl L. Iodine intake in human nutrition: a systematic literature review. Food Nutr Res 2012; 56:19731. [PMID: 23060737 PMCID: PMC3468836 DOI: 10.3402/fnr.v56i0.19731] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 09/07/2012] [Accepted: 09/18/2012] [Indexed: 11/16/2022] Open
Abstract
The present literature review is a part of the NNR5 project with the aim of reviewing and updating the scientific basis of the 4th edition of the Nordic Nutrition Recommendations (NNR) issued in 2004. The main objective of the review is to assess the influence of different intakes of iodine at different life stages (infants, children, adolescents, adults, elderly, and during pregnancy and lactation) in order to estimate the requirement for adequate growth, development, and maintenance of health. The literature search resulted in 1,504 abstracts. Out of those, 168 papers were identified as potentially relevant. Full paper selection resulted in 40 papers that were quality assessed (A, B, or C). The grade of evidence was classified as convincing, probable, suggestive, and no conclusion. We found suggestive evidence for improved maternal iodine status and thyroid function by iodine supplementation during pregnancy. Suggestive evidence was found for the relationship between improved thyroid function (used as an indicator of iodine status) during pregnancy and cognitive function in the offspring up to 18 months of age. Moderately to severely iodine-deficient children will probably benefit from iodine supplementation or improved iodine status in order to improve their cognitive function, while only one study showed improved cognitive function following iodine supplementation in children from a mildly iodine-deficient area (no conclusion). No conclusions can be drawn related to other outcomes included in our review. There are no new data supporting changes in dietary reference values for children or adults. The rationale for increasing the dietary reference values for pregnant and lactating women in the NNR5 needs to be discussed in a broader perspective, taking iodine status of pregnant women in the Nordic countries into account.
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Affiliation(s)
- Ingibjörg Gunnarsdottir
- Unit for Nutrition Research, University of Iceland and Landspitali The National University Hospital of Iceland, Reykjavik, Iceland
| | - Lisbeth Dahl
- National Institute of Nutrition and Seafood Research (NIFES), Oslo, Norway
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8
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Iodine Content and Distribution in Thyroid Specimens from Two Patients with Graves' Disease Pretreated with Either Propylthiouracil or Stable Iodine: Analysis Using X-Ray Fluorescence and Time-of-Flight Secondary Ion Mass Spectrometry. Case Rep Endocrinol 2012; 2012:842357. [PMID: 22953073 PMCID: PMC3420651 DOI: 10.1155/2012/842357] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 09/12/2011] [Indexed: 11/29/2022] Open
Abstract
Patients with Graves' disease can be medically prepared before surgery in different ways, which may have various effects on iodine stores. Thyroid specimens were collected at surgery from two patients pretreated with propylthiouracil (PTU) and stable iodine, respectively. A quantitative analysis of iodine content was performed using X-ray fluorescence (XRF) in frozen tissue and a qualitative analysis of aldehyde-fixed material with Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS). Iodine concentrations were 0.9 mg/mL and 0.5 mg/mL in the thyroid tissue from the patients treated with PTU and stable iodine respectively. TOF-SIMS showed iodine in the follicle lumina in both. However, in the PTU case, iodine was also seen within the thyrocytes indicating accumulation of iodinated compounds from uninhibited hormone release. XRF and TOF-SIMS can be used to follow iodine distribution within the thyroid and the intricate processes following the different medical treatment alternatives in Graves' disease.
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9
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Leggett RW. A Physiological Systems Model for Iodine for Use in Radiation Protection. Radiat Res 2010; 174:496-516. [DOI: 10.1667/rr2243.1] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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10
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Thyroid volume in Swedish school children: a national, stratified, population-based survey. Eur J Clin Nutr 2010; 64:1289-95. [DOI: 10.1038/ejcn.2010.162] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Andersson M, Berg G, Eggertsen R, Filipsson H, Gramatkovski E, Hansson M, Hulthén L, Milakovic M, Nyström E. Adequate iodine nutrition in Sweden: a cross-sectional national study of urinary iodine concentration in school-age children. Eur J Clin Nutr 2008; 63:828-34. [DOI: 10.1038/ejcn.2008.46] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Vejbjerg P, Knudsen N, Perrild H, Carlé A, Laurberg P, Pedersen IB, Rasmussen LB, Ovesen L, Jørgensen T. Effect of a mandatory iodization program on thyroid gland volume based on individuals' age, gender, and preceding severity of dietary iodine deficiency: a prospective, population-based study. J Clin Endocrinol Metab 2007; 92:1397-401. [PMID: 17264188 DOI: 10.1210/jc.2006-2580] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE We aimed to evaluate prospectively the effect of 4 yr of mandatory iodization of salt (13 ppm iodine) on thyroid volume in two regional areas with respectively mild and moderate iodine deficiency. METHODS Two separate cross-sectional studies were performed before (n=4649) and after (n=3570) the iodization in year 2000 in two areas with mild and moderate iodine deficiency. Women aged 18-22, 25-30, 40-45, and 60-65 yr and men aged 60-65 yr were examined. Thyroid ultrasonography was performed. RESULTS A lower median thyroid volume was seen in all age groups after iodization. The largest relative decline was found among the younger females from the area with previous, moderate iodine deficiency. Only a minor decrease was seen among the youngest participants in the area with previous, mild iodine deficiency. After iodization, there were no regional differences in median thyroid volume in the age groups younger than 45 yr. When adjusted for confounders, a lower mean volume was seen among those with multiple nodules in both areas and in the group with diffuse structure in the area with moderate iodine deficiency. Before the iodization, 17.6% of the total cross-section had thyroid enlargement; after the iodization, 10.9% of the cross-section had thyroid enlargement. CONCLUSION In this prospective study, we demonstrated a lower thyroid volume in all age groups after iodization of salt. The decline was largest in the area with former, moderate iodine deficiency. The equal volumes in the regions among the younger age groups indicate approximation to an optimal iodine intake.
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Affiliation(s)
- Pernille Vejbjerg
- Department of Internal Medicine I, Bispebjerg Hospital, University of Copenhagen, Denmark.
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13
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Milakovic M, Berg G, Eggertsen R, Nyström E, Olsson A, Larsson A, Hansson M. Determination of intrathyroidal iodine by X-ray fluorescence analysis in 60- to 65-year olds living in an iodine-sufficient area. J Intern Med 2006; 260:69-75. [PMID: 16789981 DOI: 10.1111/j.1365-2796.2006.01660.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES X-ray fluorescence (XRF) is a non-invasive method for determining the iodine content of the thyroid gland in vivo. In spite of the obvious clinical value of such a method in situations of iodine deficiency or iodine overload, the method has not so far been widely used. The objective was to investigate the applicability of the XRF method in a larger number of subjects. DESIGN AND SUBJECTS The study comprised 37 individuals, aged 60-65 years, who had spent their entire life with iodine supplementation through iodinated table salt. Individuals with (previous) thyroid disease were excluded. The individual thyroid function had previously been evaluated by measurements of thyroid-related hormones, thyroid volume and 131-Iodine (131I) uptake which indicated a sufficient iodine intake of the population in the area. Iodine in the right thyroid lobe in each subject was examined using XRF. RESULTS The mean thyroid iodine concentration was 0.4 mg mL(-1), corresponding to a mean total iodine content of 5.2 mg (range 0.9-20.2). There was a pronounced difference between individuals. No correlation was found between iodine concentration and 131I uptake or thyroid volume. Neither was iodine content and 131I uptake correlated. CONCLUSIONS In a population living under iodine-sufficient conditions, a large variation of iodine stored in the thyroid is compatible with euthyroidism. Determination of the iodine pool by XRF investigation is feasible in a clinical setting and the method offers a unique possibility to study the intrathyroidal iodine pool in subjects with thyroid disease. The low radiation dose enables the use of the method in pregnant women and also in young individuals.
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Affiliation(s)
- M Milakovic
- Department of Primary Health Care, Mölnlycke Primary Health Care and Research Centre, Mölnlycke, Sweden
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14
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Carlé A, Laurberg P, Pedersen IB, Knudsen N, Perrild H, Ovesen L, Rasmussen LB, Jorgensen T. Epidemiology of subtypes of hypothyroidism in Denmark. Eur J Endocrinol 2006; 154:21-8. [PMID: 16381987 DOI: 10.1530/eje.1.02068] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Studies of hypothyroidism are often based on referred patients, and limited information is available on the incidence rates of subtypes of hypothyroidism in the general population. We therefore studied incidences of subtypes of primary, overt hypothyroidism in a Danish population cohort and compared incidences in two subcohorts with different levels of iodine intake. DESIGN A prospective population-based study, monitoring a well-defined cohort representative of the Danish population. METHODS The Danish Investigation of Iodine Intake and Thyroid Diseases registry of hyper- and hypothyroidism was established as part of the monitoring of the iodine fortification of salt in Denmark. A computer-based system linked to laboratory databases identified all patients diagnosed with new, biochemically overt hypothyroidism in populations living in Aalborg (moderate iodine deficiency, n = 311,102) and Copenhagen (mild iodine deficiency, n = 227,632). We subsequently evaluated all identified patients to verify incident thyroid disease, and subclassified hypothyroidism into nosological types. RESULTS During a 4-year period (2,027,208 person-years) 685 new cases of overt hypothyroidism were diagnosed in the cohort; the incidence rate was 32.8 per 100,000 person-years (standardised to the Danish population). Nosological types of hypothyroidism were: spontaneous (presumably autoimmune) 84.4%, post-partum 4.7%, amiodarone-associated 4.0%, subacute thyroiditis 1.8%, previous radiation or surgery 1.8%, congenital 1.6% and lithium-associated 1.6%. Crude incidence rates were 29.0 around Aalborg and 40.6 in an area of Copenhagen. The higher incidence rate of hypothyroidism in the area with higher iodine intake was caused solely by more cases of spontaneous (presumably autoimmune) hypothyroidism, whereas the incidence of non-spontaneous hypothyroidism (all types combined) was significantly lower in the area with higher iodine intake. CONCLUSION In a population-based study we observed a higher incidence of hypothyroidism with higher iodine intake. This was due solely to the entity of spontaneous hypothyroidism. The occurrence of overt hypothyroidism was relatively low in Denmark.
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Affiliation(s)
- Allan Carlé
- Department of Endocrinology and Medicine, Aalborg Hospital, Aarhus University Hospital, DK-9000 Aalborg, Denmark.
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15
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Milakovic M, Berg G, Eggertsen R, Nyström E. Effect of lifelong iodine supplementation on thyroid 131-I uptake: a decrease in uptake in euthyroid but not hyperthyroid individuals compared to observations 50 years ago. Eur J Clin Nutr 2005; 60:210-3. [PMID: 16251883 DOI: 10.1038/sj.ejcn.1602290] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND In Sweden, iodine has been added to table salt (10 mg/kg) since 1936; this amount was increased in 1966 to 50 mg/kg. OBJECTIVE To investigate a euthyroid Swedish population (n = 44, 60-65 years) with its entire lifespan with iodine supplementation as for 24-h 131-I uptake (24 h IU) and thyroid nodularity (thyroid scintigraphy). To compare the euthyroid 24 h IU with uptake of thyrotoxic individuals, and with observations from 1955. METHODS The 24 h IU was used in euthyroid individuals after oral administration of 0.1 MBq/2.7 microCi radioiodine and imaging of the thyroid gland was carried out using 99mTc-pertechnetate. RESULTS In 1999-2000, the mean 24 h IU in the euthyroid individuals was 21% (range 11-33%) and the normal (central 95%) reference interval was 14-30%. Scintigraphy suggested multinodular goitre in three euthyroid individuals. In Graves' patients (n = 53, 50-65 years), the mean 24 h IU was 61% (range 29-89%). In 1955, the 24 h IU in euthyroid individuals was higher (38%, range 10-70%), while hyperthyroid patients had uptake values similar to those recorded in the present investigation (mean 62%, range 40-90%). CONCLUSIONS The population sample studied had to be small for ethical reasons. We conclude that the reference interval for 24 h IU is 14-30% in this population that had spent its entire lifespan with iodine supplementation. This is lower than that recorded in a Swedish euthyroid population half a century ago having had low-grade table-salt iodine supplementation for 20 years. Values for hyperthyroid patients, however, do not appear to have been affected likewise.
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Affiliation(s)
- M Milakovic
- Mölnlycke Primary Health Care and Research Centre, Department of Primary Health Care, Sahlgrenska Academy at Göteborg University, Sweden
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