Effect of the transition from more than adequate iodine to adequate iodine on national changes in the prevalence of thyroid disorders: repeat national cross-sectional surveys in China.

OBJECTIVE: Longitudinal studies have investigated the effects of changing iodine status on thyroid disorders, but the effect of a transition from more than adequate iodine to adequate iodine on national changes in prevalence adjusted for changing risk factors remains unclear. DESIGN: Two repeat nationwide surveys were conducted from 2009-2010 to 2015-2017 to assess changes in thyroid disorder prevalence and iodine status in China. METHODS: A multistage stratified random sampling method was used to obtain a nationally representative sample of urban adults aged 18 and older in mainland China in 2009 (n = 14 925) and 2015 (n = 12 553). Changes in thyroid disorder prevalence, urinary iodine concentration (UIC), and thyroid-stimulating hormone (TSH) levels were assessed. Logistic regression models were used to examine changes in prevalence over time. RESULTS: The median UIC decreased significantly from 219.7 to 175.9 µg/L (P < 0.0001). The weighted prevalence of overt hyperthyroidism, subclinical hyperthyroidism, Graves' disease, and goitre decreased between 2009 and 2015 in the overall population (P < 0.05 for all). Despite no significant changes in subclinical hyperthyroidism or hypothyroidism or anti-thyroid peroxidase or anti-thyroglobulin antibody positivity prevalence, a significant increase in thyroid nodule prevalence (P < 0.0001) was found in the overall population. The 2.5th TSH percentile increased by 0.15 mIU/L (95% CI: 0.01 to 0.30 mIU/L, P = 0.04) from 2009 to 2015. CONCLUSIONS: With the iodine status transition from more than adequate to adequate, thyroid disorder (except for thyroid nodules) prevalence remained stable or even decreased after adjusting for confounding factors among adults in mainland China between 2009 and 2015. Additional studies are needed to explore the reasons for the increased thyroid nodule prevalence.

GLOBAL ENDOCRINOLOGY: Global perspectives in endocrinology: coverage of iodized salt programs and iodine status in 2020.

Iodine deficiency has multiple adverse effects on growth and development. Diets in many countries cannot provide adequate iodine without iodine fortification of salt. In 2020, 124 countries have legislation for mandatory salt iodization and 21 have legislation allowing voluntary iodization. As a result, 88% of the global population uses iodized salt. For population surveys, the urinary iodine concentration (UIC) should be measured and expressed as the median, in µg/L. The quality of available survey data is high: UIC surveys have been done in 152 out of 194 countries in the past 15 years; in 132 countries, the studies were nationally representative. The number of countries with adequate iodine intake has nearly doubled from 67 in 2003 to 118 in 2020. However, 21 countries remain deficient, while 13 countries have excessive intakes, either due to excess groundwater iodine, or over-iodized salt. Iodine programs are reaching the poorest of the poor: of the 15 poorest countries in the world, 10 are iodine sufficient and only 3 (Burundi, Mozambique and Madagascar) remain mild-to-moderately deficient. Nigeria and India have unstable food systems and millions of malnourished children, but both are iodine-sufficient and population coverage with iodized salt is a remarkable 93% in both. Once entrenched, iodine programs are often surprisingly durable even during national crises, for example, war-torn Afghanistan and Yemen are iodine-sufficient. However, the equity of iodized salt programs within countries remains an important issue. In summary, continued support of iodine programs is needed to sustain these remarkable global achievements, and to reach the remaining iodine-deficient countries.

What is the availability of iodised salt in supermarkets on the Island of Ireland?

Iodine deficiency remains a global nutritional public health challenge, with evidence suggesting borderline adequate or even deficient status for UK and Irish subpopulations such as schoolgirls and pregnant women. The solution, according to the WHO, is salt iodisation, but it is not known how widely available iodised salt is in supermarkets. Iodised salt availability was determined by a shelf survey of 89 supermarket stores on the island of Ireland (n = 30 in Northern Ireland and n = 59 in the Republic of Ireland) from September 2018 to January 2019, to take into account factors such as store type, location, population density, socioeconomic status and ethnicity. Availability was calculated as the number of stores selling iodised salt as a percentage of the total. Iodised salt was only available in 11 stores (12%), of which 10 were ethnic stores. This indicates a lack of access for the majority of the Irish and Northern Irish populations.

Medico-social effectiveness of biological monitoring of iodine deficiency status (IDS) among women of reproductive age in Kazakhstan.

INTRODUCTION: Iodine deficiency is one of the most important public health problems in the world. It mostly affects pregnant women and children. The lack of iodine leads to an increase in the numbers of perinatal mortality and mental retardation. MATERIAL AND METHODS: In 2012-2014, a survey was carried out of 2,342 women, of whom 2284 were analyzed for salt to measure the content of iodine, and 2,242 women of reproductive age had their urine samples analyzed by the cerium-arsenite method based on the Sandell-Kolthoff reaction. Determination of the medical and social effectiveness of biological monitoring of IDS was carried out in 3 stages. RESULTS: The study revealed that in the eastern Kazakhstan region the relative risk (RR) of overall prevalence of iodine deficiency among women was 1.1 times higher (95% ID: 0.35-3.61; Z statistic = 0.192) among household respondents (≤15mkg/kg). In the Pavlodar region, the RR of the prevalence of total iodine deficiency is 0.5 times higher in households where the salt was not sufficiently iodized. In the Zhambyl region the RR of the iodine deficiency prevalence was about twice as high due to insufficient iodized salt. CONCLUSIONS: The introduction of biological monitoring of IDS among women, especially pregnant women, may positively affect the detection of the risk limits for the birth of infants with reduced mental abilities or other diseases during pregnancy, using timely targeted preventive measures to exclude factors that affect the spread of IDS.

Factors associated with the availability of iodized salt at household level: a case study in Bangladesh.

OBJECTIVE: The availability of iodized salt in households remains low in Bangladesh, which calls for improving the salt iodization quality and its coverage. The present study assessed the socio-economic disparity in Bangladesh to characterize the availability of iodized salt at household level. DESIGN: Associations between different socio-economic factors and availability of iodized salt at household level were explored using Bayesian mixed-effects logistic models after adjusting the district- and cluster-level random effects. SETTING: Bangladesh Multiple Indicator Cluster Survey (MICS), 2012-13.ParticipantsHouseholds (sample size, n 50981). RESULTS: Results showed that 73·15 % of household salt samples were iodized to some extent although iodization level varied. According to the regression model, houses with young (adjusted odds ratio of posterior mean (OR) = 1·31; 95 % credible interval (CI) 1·09, 1·64) and educated (OR = 3·66; 95 % CI 3·25, 4·23) household heads had significantly higher likelihood of availability of iodized salt. In addition, iodized salt was less likely be found in poor and rural households, as urban households were 2·88 times (95 % CI 2·41, 3·34) more likely have iodized salt. Moreover, the regional locations of the households were an important component that contributed to the local iodized salt coverage. As per the district-wise distribution, the north-west part of Bangladesh and Cox's Bazar in the far south seemed to lack household-level iodized salt. CONCLUSIONS: Our findings suggest that iodized salt intervention should be promoted considering the area variations, which could potentially help policy makers to design interventions in the context of Bangladesh.

Monitoring of salt iodisation programme in Iran; Health outcomes, shortages and perspective.

Iodine deficiency disorders include a wide range of metabolic and nonmetabolic disorders including goiter. To control IDDs, the World Health Organization and responsible agencies in countries established daily iodine uptake. Almost all the countries in the world provide the required iodine through salt iodisation. IDDs are not completely eradicable, so monitoring the salt iodisation programme is necessary for control of IDDs. In Iran, a salt iodisation programme was started in 1996. In this study, we took salt samples from all legally produced salt brands in Iran in 30 provinces and measured iodine concentration. The results of the monitoring programme for iodine concentration in schoolchildren's urine was used to compare accessibility to iodized salts and health outcomes. The results show that more than 80% of available salts have a suitable or acceptable concentration of iodine. Despite large variance in iodine concentration in available salt in some provinces, the median of iodine concentration in salts is within an acceptable range. Also, the urinary concentration of iodine (national median = 161) confirms that shortage of iodine intake is very low in Iran. The high rate of salt consumption of the Iranian people also has a significant effect on iodine uptake, but can lead to hyperthyroidism and hypertension that must be controlled.

Iodine in dairy milk: Sources, concentrations and importance to human health.

Milk and dairy products are major iodine sources in industrialized countries. However, consumption of milk and dairy, as well as their iodine concentrations, vary widely, making them an unpredictable iodine source. Milk iodine concentrations in industrialized countries range from 33 to 534 µg/L and are influenced by the iodine intake of dairy cows, goitrogen intake, milk yield, season, teat dipping with iodine-containing disinfectants, type of farming and processing. We estimate milk and dairy contribute ≈13-64% of the recommended daily iodine intake based on country-specific food intake data. To ensure adequate iodine levels but avoid the risk of iodine excess through milk and dairy, it is crucial to reduce the wide variations in milk iodine. If iodine intakes from iodized salt fall because of public health efforts to reduce salt intake, milk and dairy products may become increasingly important sources of dietary iodine in the future.

Historical aspects of iodine deficiency control.

In 1895, iodine was characterized as an essential element of thyroid tissue by Baumann. The efficacy of iodine to prevent goiter was demonstrated by Marine in Northern USA in 1916-1920. Severe endemic goiter and cretinism had been almost entirely eliminated from continental Western Europe and Northern America before the 1930's; however large populations elsewhere and even some places in Western Europe (Sicily) were still affected up to the 2000's. Public health consequences of iodine deficiency are not limited to endemic goiter and cretinism. Iodine deficiency disorders include also increased neonatal death rate and decreased intellectual development, although these consequences are not included in the current estimation of the Global Burden Disease related to iodine deficiency. Severe iodine deficiency as a public health problem is now largely under control worldwide, but can still affect isolated places, in hard-to-reach and/or politically neglected populations. We emphasize the importance of maintaining international cooperation efforts, in order to monitor iodine status where iodine deficiency is now adequately controlled, and identify at-risk population where it is not. The goal should be now global eradication of severe iodine deficiency. Commercial distribution of iodized salt remains the most appropriate strategy. A randomized clinical trial in New Guinea clearly showed in the 1970's that correcting severe iodine deficiency early in pregnancy prevents endemic neurological cretinism. This supports the essential role of thyroid hormones of maternal origin on the normal fetal development, during the first trimester of pregnancy (i.e. when fetal thyroid is still not functional). A randomized clinical trial in Congo (RD) in the 1970's also showed that correcting severe iodine deficiency during pregnancy prevents myxœdematous cretinism, particularly prevalent in affected Congolese areas.

The way forward in Italy for iodine.

Italy is dealing with iodine deficiency since ancient times. In 1848 an ad hoc committee appointed by the king of Sardinia, identified extensive areas afflicted by endemic goiter and endemic cretinism in Piedmont, Liguria and Sardinia. Since then many epidemiological studies have been conducted in our country. These showed that iodine deficiency was present not only in mountain areas but also in coastal areas. In 1972 the iodization of salt at 15 mg/kg was allowed by law and iodized salt was distributed on request to selected endemic areas. Five years later the distribution was extended to the whole country. However the sale of iodized salt was not mandatory at that time and only a small fraction of the Italian population started using iodized salt. In 1991 the content of iodine in the salt was raised to 30 mg/kg and in 2005 a nationwide salt iodization program was finally implemented. Some years later a nationwide monitoring program of iodine prophylaxis was also implemented. Since 2005 the sale of iodized salt in Italian supermarkets has increased (34% in 2006, 55% in 2012), although it has been observed that the use of iodized salt is still low in the communal eating areas and in the food industry. These data are coherent with recent epidemiological studies showing that some regions in our country are still characterized by mild iodine deficiency and a high frequency of goiter and other iodine deficiency disorders. This implies that further efforts should be made to successfully correct iodine deficiency in Italy.

The Prevalence of Thyroid Nodules and Their Association with Metabolic Syndrome Risk Factors in a Moderate Iodine Intake Area.

BACKGROUND: To investigate the prevalence of thyroid nodules (TNs) and to evaluate the association between TNs and metabolic syndrome (MetS) in the moderate iodine intake area of Jiangsu, China. SUBJECTS AND METHODS: A cross-sectional study was carried out in a Chinese community-based epidemiological investigation from January to December 2014. A questionnaire was completed by 6494 subjects (2427 men and 4067 women). Thyroid ultrasound was performed by using a 7.5-MHz linear probe. MetS was defined according to the 2006 International Diabetes Federation criteria. RESULTS: The prevalence of TNs in the study population was 17.7% (12.9% for men and 20.6% for women) and significantly higher in subjects with MetS [MetS(+)] than in those without MetS [MetS(-)] (25.8% vs. 15.5%, χ2 = 78.471, P < 0.001). Binary logistic regression indicated that (in addition to female sex and increased age) increased fasting plasma glucose (FPG), waist circumference (WC), hypertension, and smoking were positively associated with the prevalence of TNs. CONCLUSIONS: Our findings indicated a positive association between MetS and formation of TNs. Increased WC and FPG, as well as hypertension, might increase the prevalence of TNs.

Access to iodized salt in 11 low- and lower-middle-income countries: 2000 and 2010.

OBJECTIVE: To describe changes in household access to iodized salt in relation to socioeconomic factors. METHODS: We extracted data on iodized household salt from Multiple Indicator Cluster Surveys conducted in 2000 and 2010. As part of the surveys, household salt samples were tested for iodization by standardized rapid-test kits that yield results to indicate whether salt is not iodized, inadequately iodized, (less than 15 parts per million, ppm), or adequately iodized (more than 15 ppm). We calculated indices of household salt iodization in 2000 and 2010, taking into account survey sampling weights. We explored associations between these indices and socioeconomic variables, both within and between countries. FINDINGS: We analysed data from 105 162 households in 2000 and 144 018 households in 2010. Between 2000 and 2010, household coverage of adequately iodized salt increased by 6.1% (from 46.3% to 52.4%) on average, but with regional differences: coverage fell by 13.0% (from 77.5% to 64.5%) in the Central African Republic but improved by 40.4% (from 22.2% to 62.6%) in Sierra Leone. Improvements in coverage were higher in rural areas and among the poorest households, but within-country socioeconomic disparities remained. There were weak associations between changes in salt iodization and national level socioeconomic indicators. CONCLUSION: Overall, the coverage of adequately iodized household salt increased over the last decade. However, the changes varied widely among countries. The goal of universal salt iodization is still distant for many countries and requires renewed efforts by governments, bilateral and multilateral agencies and civil society.

Mild iodine deficiency in women after spontaneous abortions living in an iodine-sufficient area of Czech Republic: prevalence and impact on reproductive health.

OBJECTIVE: Iodine deficiency is associated with thyroid dysfunction and adverse pregnancy outcomes. The aim of our study was to investigate the status of iodine saturation in women after spontaneous abortion (SpA) residing in an iodine-sufficient area and to evaluate their subsequent reproductive health. DESIGN: Nonrandomized prospective follow-up study. PATIENTS AND METHODS: We compared urinary iodine concentration (UIC) in 171 women 2-8 weeks (median 4) after an early SpA with age-matched controls. Women with known thyroid diseases were excluded. We also analysed a relationship of UIC to serum thyroid-stimulating hormone, free thyroxine, antibodies against thyroid peroxidase and thyroid ultrasound. Afterwards, we followed the women for a median of 38 months (range 12-47). We used a multivariate regression analysis to assess the influence of iodine status and other thyroid biochemical and ultrasound parameters on their subsequent reproductive health. RESULTS: Women after SpA were almost twice as likely to suffer from mild iodine deficiency and had lower median UIC as compared to age-matched controls [rate 105/181 (58·0%) vs 57/181 (31·5%), P < 0·001, medians UIC 92·00 vs 117·80 mcg/l, P < 0·001]. UIC was not influenced by the use of iodine supplements in the previous pregnancy. We did not find any association neither between UIC and thyroid dysfunction and/or thyroid antibodies, nor between UIC and rates of subsequent successful pregnancies or obstetric complications. CONCLUSIONS: More than half of women after SpA residing in an iodine-sufficient area are suffering from mild iodine deficiency. However, it does not seem to have a negative impact on their subsequent reproductive health.

Availability of iodised table salt in the UK - is it likely to influence population iodine intake?

OBJECTIVE: Iodine deficiency has recently been found in UK young and pregnant women, which is of concern given the importance of adequate iodine intake in pregnancy for fetal brain development. The WHO recommends that iodine deficiency in a population should be corrected through salt iodisation but there is a lack of UK data on iodised-salt availability, a situation that the present study aimed to address. DESIGN: Availability of iodised salt for household use was determined by a shelf survey in five supermarket chains in each of sixteen UK areas (in Southern England, Wales and Northern Ireland) encompassing a total of seventy-seven supermarkets. All branches of a sixth supermarket chain that had 2·3% of the market share sold exclusively iodised salt. Weighted iodised-salt availability was calculated taking the market share of supermarkets into account. SETTING: The UK. SUBJECTS: Not applicable. RESULTS: Iodised salt was available in thirty-two of the seventy-seven supermarkets (41·6%). After accounting for market share and including all six UK supermarket chains, the weighted availability of iodised salt was 21·5%. The iodine concentration of the major UK brand of iodised salt is low, at 11·5 mg/kg. CONCLUSIONS: In contrast to other countries, iodised household table salt is unlikely to contribute meaningful amounts to UK iodine intake as (i) availability is low, (ii) table salt is only a small percentage of total UK salt intake and (iii) UK public-health campaigns have encouraged reduced salt consumption. As iodine intake in the UK is dependent entirely on food choices, regular monitoring of iodine status is essential.

Evolution of iodine deficiency disorders control program in India: a journey of 5,000 years.

Iodine deficiency disorders (IDD) has been documented since around 5,000 years. However, geological factors like frequent glaciations, flooding, and changing of course of rivers has led to iodine deficiency in soil. As a result everyone remains at risk of IDD, if optimum intake of iodine is not sustained. Evolution of the IDD control program in India has been a dynamic process. The model of IDD control program in India provides important lessons for successful implementation of a national health program. In formulating National Health Programs; policy environment, scientific inputs, political will, and institutional structure for decision making are necessary but not sufficient. Continuous and dynamic generation of reliable and representative state and national level data, proactive recognition of values of key stakeholders and addressing them through sustained advocacy, development of partnerships among stakeholders, institutional continuity, and mentorship are critical for achieving sustainability of results.

Reaching the poor with adequately iodized salt through the Supplementary Nutrition Programme and Midday Meal Scheme in Madhya Pradesh, India.

PROBLEM: In India, adequately iodized salt needs to be made accessible to the most marginalized. APPROACH: In an effort to provide adequately iodized salt to the most vulnerable, in 2009 Madhya Pradesh launched a state-wide initiative through two national flagship nutrition programmes: the Supplementary Nutrition Programme of the Integrated Child Development Services and the Midday Meal Scheme. Programme staff members were taught how to correctly store salt and monitor its iodine content. Field monitors assessed the iodine content of the salt in the common kitchens of participating schools and anganwadi centres monthly. LOCAL SETTING: Madhya Pradesh, a state in central India, is home to a substantial proportion of India's poor. In 2009, household coverage of adequately iodized salt in the state was nearly 90% among the richest but only about 50% among the poorest. RELEVANT CHANGES: Two hot meals prepared with adequately iodized salt were served daily for more than 21 days per month to approximately 89% of the 12,113,584 children aged 3 to 6 years enrolled in anganwadi centres (June 2011 to March 2012). One meal on school days was served to 78% of 5,751,979 primary-school children and to 79% of 2,704,692 secondary-school children (April 2011 to March 2012). Most of the kitchens visited in 2010 (79%) and 2011 (83%) were consistently using adequately iodized salt to prepare hot meals. LESSONS LEARNT: India has large-scale social safety net programmes for the poorest. Both national and state policies should mainstream the use of adequately iodized salt in these programmes.

Increase in iodine deficiency disorder due to inadequate sustainability of supply of iodized salt in District Solan, Himachal Pradesh.

Himachal Pradesh is a known endemic area for iodine deficiency disorders. A study was conducted in district Solan with the objective of assessing the prevalence of iodine deficiency disorders in school-age children. Thirty clusters were selected by using the probability-proportionate-to-size cluster sampling methodology. Clinical examination of the thyroid of 1898 children in the age-group of 6-12 years was conducted. Urine and salt samples were collected. The total goiter rate was found to be 15.4%. Median urinary iodine excretion level was 62.5 µg/l. Only 39% of the salt samples had iodine content of ≥15 ppm. Mild iodine deficiency was present in the subjects studied.

Does smoking affect thyroid gland enlargement and nodule formation in iodine-sufficient regions?

OBJECTIVES: The present study aimed to investigate the effect of smoking on thyroid nodule formation and goiter development in healthy subjects living in Istanbul, an iodine-sufficient region. This study was designed as a prospective, randomized, and observational study. METHODS: Included in the study were voluntary hospital staff and relatives of patients between the ages of 28 and 71 who had no known disease or drug use, who have been living in Istanbul and had been smoking more than 10 cigarettes per day for at least 10years. Nonsmoker volunteers (45) shared similar demographic characteristics and were matched for age to the (46) smokers. By means of thyroid ultrasounds performed in all participants, volumes of the right and left lobes of the thyroid gland, and number, diameter and characteristics of nodules were evaluated. RESULTS: Comparing the smokers and nonsmokers, no statistically significant difference was determined in terms of presence of nodules and volumes of the left and right thyroid lobes (P=0.68, P=0.09, and P=0.63, respectively). Making enhanced diffuse enlargement of the thyroid gland, but not to a statistically significant degree. Smoking was observed to have no effect on non-toxic nodules, or the levels of thyroid-stimulating hormone, free thyroxin, free triiodothyronine, anti-thyroid peroxidase, or anti-thyroglobulin antibodies. CONCLUSIONS: Smoking does not effect, to a statistically significant degree goiter development thyroid nodule formation in iodine-sufficient regions like Istanbul.

Knowledge of iodoprophylaxis and iodized salt consumption among medical students in Italy.

OBJECTIVES: Iodine deficiency is still a notable health-care problem in several regions of Europe and can be responsible for maternal and fetal goiter, miscarriages, stillbirths, reduced fetal growth, congenital hypothyroidisms, damaged reproduction in adult life, and inadequate development and maturation of the fetal brain, which is the major preventable cause of mental defects. The aim of this study was to assess the medical students' knowledge and practices regarding the program of iodized-salt-use and active iodine prophylaxis program launched by the Italian Ministry of Health. MATERIALS AND METHODS: A self-administered, anonymous, 19 single-item questionnaire was developed. We have collected 294 filled forms: 86 from first-year, 118 from fourth-year and 90 from sixth-year medical students at the First Medical School of 'Sapienza' University of Rome, Italy, in May 2009. RESULTS: Two hundred eighty four students (96.6%) affirm that they know of the existence iodized salt, even though only 199 (67.7%) report personal consumption. This level is quite far from the target (consumption by almost 80% of the general population) suggested by the international literature. No statistically relevant difference was observed between the answers of male and female students. CONCLUSIONS: Our study proves that clinical students have a more detailed knowledge on iodized salt if compared with pre-clinical students, but such knowledge remains overall defective and in some cases absolutely incorrect. Additional education is probably needed to prepare physicians to play a critical role in counseling about iodine prophylaxis.