The Status of Iodine Nutrition and Thyroid Disorders in China: Two Decades After the Universal Salt Iodization

2018 ◽  
Author(s):  
Zhongyan Shan ◽  
Weiping Teng ◽  
Yongze Li ◽  
Guang Ning ◽  
Yiming Mu ◽  
...  
2019 ◽  
Vol 15 (2) ◽  
pp. 38-41
Author(s):  
Michael B. Zimmermann

The status of iodine nutrition is a key factor in determining the prevalence of thyroid disorders in adults. The study under discussion provides data on the change in the incidence of nosological subtypes of overt thyrotoxicosis and hypothyroidism in adults during an increase in iodine intake after the introduction of mandatory salt iodization in Denmark. The authors carefully studied the case histories of all new patients with thyrotoxicosis and hypothyroidism registered in 2014–2016 in an open cohort of the population of Northern Jutland (n = 309,434), in which a moderate iodine deficiency has historically been observed and compared with incidence rates in 1997–1998 years before introduction of mandatory salt iodization began 2001. Over this period of time, iodine intake almost doubled. At the same time, the incidence rate of confirmed overt thyrotoxicosis significantly decreased: from the initial rate of 97.5 cases per 100,000 people per year in 1997–2000 to 48.8 cases per 100,000 people per year in 2014–2016. This result was due to a significant decrease in the incidence of multinodular toxic goiter, toxic adenoma and Graves’ disease in all age groups in both women and men. Moreover, the overall incidence of primary overt hypothyroidism has not changed.


2000 ◽  
pp. 189-196 ◽  
Author(s):  
F Delange ◽  
A Van Onderbergen ◽  
W Shabana ◽  
E Vandemeulebroucke ◽  
F Vertongen ◽  
...  

OBJECTIVE: Belgium is one of the Western European countries in which no program of iodine-deficiency correction using iodized salt has been implemented, in spite of well-documented mild iodine deficiency. In 1995, the median urinary iodine concentration was 55 microg/l (normal: 100-200) and the prevalence of goiter was 11% (normal: below 5%) in representative samples of schoolchildren aged 6-12 years. Based on these results, the authors of the present study and others had emphasized to health professionals and to the public the necessity for iodine supplementation. The objective of this study was to evaluate as to whether these efforts had resulted in an improvement in the status of iodine nutrition. DESIGN: We performed a national survey of the status of iodine nutrition in Belgium based on the determination of thyroid volume, obtained by ultrasonography, and urinary iodine concentrations in schoolchildren. METHODS: A mobile van equipped with an ultrasound instrument, a computer and a deep-freeze visited 23 schools selected from across the country. The sample included 2855 schoolchildren (1365 boys and 1490 girls) aged 6-12 years. RESULTS: The results show a homogeneous situation in the whole country, with a median urinary iodine concentration of 80 microg/l and a goiter prevalence of 5.7%. Urinary iodine slightly decreases with age in girls and reaches a critical value of 59 microg/l at the age of 12 years, together with a goiter prevalence of 18.4%. CONCLUSION: Iodine nutrition has improved slightly in Belgium but mild iodine deficiency continues, with public-health consequences. The improvement indicates silent iodine prophylaxis, as no official salt-iodization measures have been taken. Silent iodine prophylaxis only partly corrects iodine deficiency in Western Europe. Active measures, including the implementation of a program of salt iodization, are urgently required.


2005 ◽  
Vol 26 (3) ◽  
pp. 255-258 ◽  
Author(s):  
Umesh Kapil ◽  
Thakur Dutt Sharma ◽  
Preeti Singh ◽  
Sada Nand Dwivedi ◽  
Supreet Kaur

Background A survey conducted by the central iodine-deficiency disorders team in Himachal Pradesh, a state in the goiter-endemic belt of India, revealed that 10 of its 12 districts have an endemic prevalence of goiter. The survey was conducted to provide health program managers data to determine whether it would be necessary to initiate intervention measures. Objective To assess the status of urinary iodine excretion and household salt iodization levels after three decades of a complete ban on the sale of noniodized salt in this goiter-endemic state in India as measured by assessment of urinary iodine excretion levels and iodine content of salt at the household level. Methods The guidelines recommended by WHO/UNICEF/ICCIDD for a rapid assessment of salt iodization were adopted. In each of the 12 studied districts, all senior secondary schools were enlisted and one school was selected by using a random sampling procedure. Two hundred fifty children 11 to 18 years of age were included in the study. Urine samples were collected from a minimum of 170 children and analyzed using the wet digestion method. Salt samples were also collected from a minimum of 170 children and analyzed using the spot testing kit. Results All districts had a median urinary iodine excretion level > 200 μg/L and 82% of the families were consuming salt with an iodine content of 15 ppm or higher. Conclusions The results of the present study highlight the successful implementation of the salt iodization program in the state of Himachal Pradesh. This positive impact may be due to the comprehensive strategy adopted by the state government to improve the quality of salt, development of an effective monitoring information system and effective information, education, and communication activities.


2017 ◽  
Vol 39 (1) ◽  
pp. 75-85 ◽  
Author(s):  
Fan-Fen Wang ◽  
Kam-Tsun Tang ◽  
Wen-Harn Pan ◽  
Justin Ging-Shing Won ◽  
Yao-Te Hsieh ◽  
...  

Background: In 2003, Taiwan’s iodine policy changed from mandatory to voluntary. The Nutrition and Health Survey in Taiwan (NAHSIT) 2001-2002 for schoolchildren showed adequate iodine nutrition, while NAHSIT 2005-2008 for adults showed the iodine status was at borderline adequacy. Objective: To investigate the iodine status of the Taiwanese population from schoolchildren to adulthood 10 years after the change of the salt iodization policy. Method: Urinary iodine was measured in samples from subjects in NAHSIT 2013. Results: The median urinary iodine concentration (UIC) of the Taiwanese population aged 6 years and above in 2013 was 96 μg/L, indicating mild iodine deficiency. The median UIC of 6- to 12-year-old schoolchildren was 124 μg/L (interquartile range [IQR]: 92-213 μg/L), and 115 μg/L (IQR: 80-166 μg/L), 125 μg/L (IQR: 74-161 μg/L), 73 μg/L (IQR: 52-131 μg/L), and 78 μg/L (IQR: 52-132 μg/L) in populations aged 13 to 18 years, 19 to 44 years, 45 to 64 years, and ≥65 years, respectively. Declining iodine nutrition in age groups ≥45 years old was noted that the median UIC of populations aged 45 to 64 years and ≥65 years was 99 and 88 μg/L, respectively, in NAHSIT 2005-2008. The median UIC of schoolchildren was not lower than that during the mandatory salt fortification period, but the distribution of urinary iodine levels signified a dietary pattern change. Conclusion: Wide-ranging variation in iodine nutrition levels was observed in different age groups. Universal salt iodization, as suggested by the World Health Organization, should be the best strategy to achieve adequate iodine nutrition.


2018 ◽  
Vol 148 (4) ◽  
pp. 587-598 ◽  
Author(s):  
Susanne Dold ◽  
Michael B Zimmermann ◽  
Tomislav Jukic ◽  
Zvonko Kusic ◽  
Qingzhen Jia ◽  
...  

Author(s):  
Li-Heng Meng ◽  
Cui-Hong Chen ◽  
Ying Liu ◽  
Xing-Huan Liang ◽  
Jia Zhou ◽  
...  

Author(s):  
Mark P. J. Vanderpump

Thyroid disorders are among the most prevalent of medical conditions. Their manifestations vary considerably from area to area and are determined principally by the availability of iodine in the diet. The limitations of epidemiological studies of thyroid disorders should therefore be borne in mind when considering the purported frequency of thyroid diseases in different communities (1). Almost one-third of the world’s population live in areas of iodine deficiency and risk the consequences despite major national and international efforts to increase iodine intake, primarily through the voluntary or mandatory iodization of salt (2). The ideal dietary allowance of iodine recommended by the WHO is 150 μ‎g iodine/day, which increases to 250 μ‎g in pregnancy and 290 μ‎g when lactating. The WHO estimates that two billion people, including 285 million school-age children still have iodine deficiency, defined as a urinary iodine excretion of less than 100 μ‎g/l. This has substantial effects on growth and development and is the most common cause of preventable mental impairment worldwide. In areas where the daily iodine intake is below 50 μ‎g, goitre is usually endemic, and when the daily intake falls below 25 μ‎g, congenital hypothyroidism is seen. The prevalence of goitre in areas of severe iodine deficiency can be as high as 80%. Iodization programmes are of proven value in reducing goitre size and in preventing goitre development and cretinism in children. Goitrogens in the diet, such as thiocyanate in incompletely cooked cassava or thioglucosides in Brassica vegetables, can explain some of the differences in prevalence of endemic goitre in areas with similar degrees of iodine deficiency. Autonomy can develop in nodular goitres leading occasionally to hyperthyroidism, and iodization programmes can also induce hyperthyroidism, especially in those aged over 40 years with nodular goitres. Autoimmune thyroiditis or hypothyroidism has not been reported to complicate salt iodization programmes. Relatively little prevalence data exist for autoimmune thyroid disease in areas of iodine deficiency (3). In iodine-replete areas, most people with thyroid disorders have autoimmune disease, ranging through primary atrophic hypothyroidism, Hashimoto’s thyroiditis, to hyperthyroidism caused by Graves’ disease. Cross-sectional studies in Europe, the USA, and Japan have determined the prevalence of hyperthyroidism, hypothyroidism, and the frequency and distribution of thyroid autoantibodies in different, mainly white, communities (1, 4–6). Recent US data have revealed differences in the frequency of thyroid dysfunction and serum antithyroid antibody concentrations in different ethnic groups (6), whereas studies from Europe have revealed the influence of dietary iodine intake on the epidemiology of thyroid dysfunction (7). Studies of incidence of autoimmune thyroid disease have only been conducted in a small number of developed countries (8–11). Following a review of the available epidemiological data, the value of screening adult populations for autoimmune thyroid disease will be considered.


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