Awareness of the implementation of stable iodine prophylaxis by parental guardians living in the urgent protective action planning zone of an operating nuclear power plant in Japan

Purpose The aim of this study was to clarify the characteristics and awareness of the need for protection against ionizing radiation, such as sheltering, evacuation, and implementing stable iodine prophylaxis, of guardians parenting young children living in an urgent protective action planning zone (UPZ) of an operating nuclear power plant in Japan. Methods Self-administered questionnaires were distributed to approximately 3000 guardians through 26 kindergartens located within a UPZ. Responses were obtained from 1172 who lived in the UPZ and were included in the analysis. Results Of the 1172 guardians, 460 (39.2%) responded that sheltering is not useful to reduce the dose of radiation exposure. On the other hand, 395 (33.7%) guardians responded that implementing stable iodine (SI) prophylaxis could prevent exposure from all radionuclides, and 876 (74.7%) responded that pregnant women should also implement SI prophylaxis in a nuclear emergency. Furthermore, 83.0% (973) responded that they wanted to receive pre-distribution of stable iodine (PDSI) for their children. On the other hand, 38.9% (456) of guardians had not known about SI before the study, and 71.8% (841) of guardians felt anxious about implementing SI prophylaxis for their children. Conclusion Most guardians had expectations regarding SI and received PDSI, but they felt anxious about implementing SI prophylaxis for their children. It is essential that guardians living in the UPZ of restarted nuclear power plants be educated, and that risk communication about protection against ionizing radiation, including the side effects of implementing SI prophylaxis and radiation health effects, be conducted.

Iodine deficiency in pregnant women and newborns in the Saratov region: current state of the problem

Introduction. Iodine deficiency remains an urgent challenge for the Russian Federation. Pregnant women should receive prophylactic potassium iodide supplements at a dose of 200–250 mcg per day. To monitor the severity of iodine deficiency in the regions and the efficacy of prenatal iodine prophylaxis, it is prudent to use the neonatal hyperthyrotropinemia rate for newborns (thyroidstimulating hormone level is higher than 5 μIU/L) based on the results of congenital hypothyroidism screening.Objective. To assess the changes in the severity of iodine deficiency and the efficacy of iodine prophylaxis in pregnant women and newborns in the Saratov region based on the incidence of neonatal hyperthyrotropinemia over the past 25 years.Materials and methods. The incidence of neonatal hyperthyrotropinemia in newborns in the Saratov region for the period of 1996–2000 and 2015–2020 was analysed. In total, 229,625 children were examined.Results and discussion. In 1996–2000, neonatal hyperthyrotropinemia was detected in 37.4% of newborns, which was evidence of the presence of moderate iodine deficiency in the region. In 2015–2020, the incidence of neonatal hyperthyrotropinemia decreased by 5.42 times to 6.9% (p < 0.0001) against the background of group iodine prophylaxis in pregnant women, but remained higher than the World Health Organization targets for iodine-rich regions (<3%) suggesting the preservation of mild iodine deficiency in pregnant women and newborns in the Saratov region.Conclusions. Despite the obligatory doctor’s prescription of prenatal group iodine prophylaxis, there is still iodine insufficiency in pregnant women and newborns in the Saratov region, which requires further improvement of the regional iodine deficiency eradication action system in the risk groups. However, significant advances in the fight against iodine deficiency in the nutrition of the Russian population can only be achieved after the adoption of the federal law on universal salt iodization.

Thyroid health in big city realities

Thyroid gland (ThG) diseases lead at structure of the endocrine diseases. At the same time ThG-diseases frequency are age-associated and depend from influence of combination of negative external risk factors (Iodine deficiency, Selenium deficiency, technogenic stress rising, environmental pollution, high level of urbanization). Iodine prophylaxis is necessary at the all age groups and requires for pregnant woman. The legislative Iodine prophylaxis predetermines primarily the reduction of the frequency of occurrence of such ThG-diseases as diffuse euthyroid goiter and nodule goiter. The appearance and progression of diffuse euthyroid goiter are more typical for rural. The adequate (without overdosing) correction of Iodine deficiency is necessary in order to avoid the hypothyroidism, what is especially important for coastal urban and rural. It is noted the rising of the frequency of occurrence of autoimmune ThG-diseases and ThG antibodies carrying, including autoimmune polyendocrine syndromes. Selenium deficiency and Vitamin D deficiency must be adjusted along with Iodine deficiency. The natural and the technogenic strumogenes negatively effluenced to ThG are considered. It was proposed to consider the frequency of occurrence of ThG-cancer as the marker of ecological pollution. It was observed the connection of depression and ThG-function. The rural inhabitation affected to the severity of depression that is more actually for postmenopausal women. At the same time the correct formation of the urban landscape (in reorganization context) promotes the maintainance of ThG’s metabolic health.

Socio-ecological and medical problems of iodine deficiency among the population of Ukraine

Aim. Study of iodine supply in different segments of the population throughout Ukraine, establishment of the morbidity level caused by iodine deficiency, analysis of preventive measures and their effectiveness and development of adequate ways of mass, group and individual prophylaxis of iodine deficiency in the body, which will reduce morbidity in areas of endemic iodine deficiency. The article considers the most important results of long-term epidemiological studies of iodine supply in different categories of the population of almost all regions of Ukraine. Significant volume of work was performed with the support of the Ministry of Healthcare of Ukraine, UNICEF Ukrainian office, and the CDC in Atlanta (USA), which for more than 19 years has provided external quality control of the study of iodine status of the population of Ukraine. The data on iodine content in food and biological fluids of the population affected by the Chernobyl accident are given and the dependence of the irradiation dose of the thyroid on the body supply with stable iodine and on the optimization of the latter after the adoption of the State Programme for Iodine Deficiency Prevention for 2002–2005 is shown. The effectiveness of mass iodine prophylaxis by using universally iodized table salt is emphasized. The article presents data on suggested and implemented ways of mass, group and individual iodine prophylaxis, studies of their effectiveness and shows the positive dynamics of changes in providing the population with dietary iodine. The need for constant consumption of food products with sufficient iodine content, including iodized salt, is proven. Significant changes in the prevalence and incidence of thyroid pathology, socio-ecological and medical benefits of prevention of iodine-dependent disorders are described. The article was prepared as a scientific information material for family doctors, endocrinologists, obstetricians and gynaecologists, hygienists, the public, the Ministry of Healthcare of Ukraine in connection with the need for a legislative solution to the prevention of iodine-dependent disorders in Ukraine. Materials and Methods. To study the problem and assess the state of iodine deficiency in Ukraine the criteria recommended by the WHO and the United Nations Children’s Fund (UNICEF) were applied for the first time, a method for determining the iodine content in the body was developed and implemented, which allowed to join the international “Equip” system of iodine supply control in the world and in Ukraine. This made it possible to move from indirect to direct methods of determining the intake of iodine in the body. Conclusions. A detailed study of iodine supply in different segments of the population of Ukraine proved the negative effects of iodine deficiency on health; in particular, it was found that the overall decrease in productivity of the generation of children in iodine deficiency populations is 5%. Measures to eliminate iodine-dependent disorder among the population of Ukraine have been developed and implemented. The development and production of iodized food salt, adequate to the needs of the population, has been carried out. The result of these measures, developed and implemented to eliminate iodine-dependent disorders and to improve the nation’s intelligence, is, according to the official data, the improvement of iodine supply of the population, significant reduction in the number of thyroid disorders, especially among those affected with 131I, which, even just because of this indicator, has significant social-economic effect. Key Words: Chernobyl accident, iodine deficiency, iodized salt, population, prevention, regions.

Iodoprophylaxis and thyroid autoimmunity: an update

Adequate iodine intake is necessary for normal thyroid function. Iodine deficiency is associated with serious complications, but also iodine excess can lead to thyroid dysfunction, and iodine supplementation aimed to prevent iodine deficiency disorders has been associated with development of thyroid autoimmunity. The epidemiology of thyroid diseases has undergone profound changes since the implementation of iodoprophylaxis, notably by means of iodine-enriched salt, specifically resulting in decreased prevalence of goiter and neonatal hypothyroidism, improved cognitive function development in infancy, and reduced incidence of more aggressive forms of thyroid cancer. The main question we address with this review is the clinical relevance of the possible effect on autoimmunity exerted by the use of iodine-enriched salt to correct iodine deficiency. In animal models, exogenous iodine is able to trigger or exacerbate thyroid autoimmunity, but it is still not clear whether the observed immunological changes are due to a direct effect of iodine on immune response, or whether they represent a secondary response to a toxic effect of iodine on thyroid tissue. Previous iodine status of a population seems to influence the functional thyroid response to increased iodine intake and possibly the development of thyroid autoimmunity. Moreover, the prevalence of thyroid antibodies, regarded as hallmark of autoimmune thyroid disease, varies between populations under the influence of genetic and environmental factors, and the presence of thyroid antibodies does not always coincide with the presence of thyroid disease or its future development. In addition, the incidence of autoimmune diseases shows a general increasing trend in the last decades. For all these reasons, available data are quite heterogeneous and difficult to analyze and compare. In conclusion, available data from long-term population surveys show that a higher than adequate population iodine intake due to a poorly controlled program of iodine prophylaxis could induce thyroid dysfunction, including thyroid autoimmunity mostly represented by euthyroid or subclinical hypothyroid autoimmune thyroiditis. Close monitoring iodine prophylaxis is therefore advised to ensure that effects of both iodine deficiency and iodine excess are avoided.

Avoidance of iodine deficiency/excess during pregnancy in Hashimoto’s thyroiditis

Purpose Hashimoto’s thyroiditis is a common disease that also affects pregnant women. We analyzed to what extent the inflammatory process of Hashimoto’s thyroiditis changes with iodine prophylaxis in pregnant women. The target for immunologic activity was levels of thyroid antibodies (TPO). Methods The data were collected retrospectively from 20 consecutive, pregnant patients who had been diagnosed with Hashimoto’s thyroiditis between 01.12.2012 and 01.12.2014 and had received iodine supplementation with 100 µg (n = 1) or 150 µg (n = 19). At least two measurements of TPO antibody levels taken during pregnancy and one after pregnancy were evaluated for each patient in the study group. Results At the end of pregnancy, the average TPO antibody level for the 20 patients studied was 137 IU/ml (+/–214 IU/ml), the lowest being 16 IU/ml and the highest 1000 IU/ml. Despite iodine prophylaxis, levels of TPO antibodies decreased in 18 patients during pregnancy, falling below the reference value of 35 IU/ml in 5 cases. However, in one patient TPO antibodies increased from 60 IU/ml to 237 IU/ml during pregnancy while in another, levels remained constant at 1000 IU/ml. Conclusion Iodine prophylaxis in pregnant women, taken at a dose of 100 or 150 μg daily was shown to have no negative systemic effects on Hashimoto’s thyroiditis in a group of pregnant women with increased TPO levels, and can therefore be recommended for expectant mothers, including those with this disease.

Armenia's experience in achieving an adequate iodine status of the population

Armenia was one of the first post-Soviet countries, that after a relatively short break has restored the production of iodized salt at the beginning of the 2000s, and in 2004 adopted a decree that made the production and import of iodized salt mandatory, as well as its use in the food industry. A 2016 national survey showed high sustainability of the iodine prophylaxis program in Armenia – median urinary iodine concentration (UIC) in schoolchildren and pregnant women (PW) was in the optimal range (242 and 226 μg/l, respectively), and coverage of households with quality iodized salt was 95%. In addition to iodized salt used in households, more than 50% of iodine was consumed with processed foods, primarily bakery products. An essential advantage of the iodine prophylaxis program in Armenia is that it provides adequate iodine status not only for the general population, but also for PW. At the same time about 37% of PW used iodine supplements, which were not necessary. The experience of Armenia shows that the analysis of screening datasets for neonatal hypothyroidism screening makes it possible to efficiently and at minimal cost annually evaluate the iodine status of the population. And if the frequency of TSH levels > 5 mIU/L exceeds 3%, the health authorities should consider this as an alarm and conduct a more detailed assessment to find out the cause of the iodine status insufficiency and take appropriate measures

No significant association between stable iodine intake and thyroid dysfunction in children after the Fukushima Nuclear Disaster: an observational study

Purpose Stable iodine prophylaxis helps prevent childhood thyroid cancer in nuclear emergencies; however, there is limited information on its effect on thyroid function. This study aimed to examine thyroid function and autoimmunity among children and adolescents that took stable iodine after the Fukushima Nuclear Disaster. Methods For this observational study, data were obtained from children and adolescents that underwent thyroid cancer screening at Hirata Central Hospital from April 2012 to March 2018. Participant characteristics, including possible hypothyroidism and hyperthyroidism, were compared between the prophylaxis and no-prophylaxis groups. Multivariable logistic regression models were used to assess for possible hypothyroidism, autoantibodies positive, and hyperthyroidism. Results A total of 1,225 participants with stable iodine prophylaxis and 3,946 without prophylaxis were enrolled. Of those participants, blood samples were available for 144 and 1,201 participants in the prophylaxis and no-prophylaxis groups, respectively. There were 17 (11.8%) and 146 cases (12.2%) of possible hypothyroidism or autoantibodies positive cases in the prophylaxis and no-prophylaxis groups, respectively, and there were no cases and 3 cases (0.2%) of possible hyperthyroidism in those two groups, respectively. Multivariable analysis for possible hypothyroidism revealed no association between stable iodine intake and possible hypothyroidism or autoantibodies positive [odds ratio 0.716 (95% confidence interval 0.399–1.284)] (p = 0.262). We did not perform multivariable analysis for hyperthyroidism due to the limited number of cases. Conclusion Significant adverse effects of stable iodine intake on thyroid function were not observed among children and adolescents 7 years after the Fukushima Nuclear Disaster.

The Use of X-ray Computed Tomography to Assess the Intrathyroidal Iodine Concentration and its Storage in the Thyroid Gland

In this lecture, the need of using X-ray computed tomography (CT) to assess the intrathyroidal iodine concentration and its storage in the thyroid gland has being discussed. Due to the fact that 80 % of intrathyroidal iodine is located in the phenolic ring of thyroid hormones, which are structurally located in colloid-thyroglobulin follicles as a hormonal depot, the parameter of intrathyroidal iodine (PII) is an indicator of the stores of iodine-containing thyroid hormones directly in the organ. A decrease in intrathyroidal iodine indicates a significant functional impairment of storing thyroid hormones in the colloid of thyroglobulin of the thyroid follicles and is an early highly accurate prognostic sign of the formation of gland dysfunction. Due to the compensatory capabilities of the body, this dysfunction may appear late onset (for example, 2 months after detecting a decrease in intrathyroidal iodine). The most convenient and affordable method for determining intrathyroidal iodine is CT with two types of tomographs: 1) standard by which intrathyroidal iodine is determined by the density of the thyroid gland in Hounsfield units (HU); 2) tomographs with the option of assessing the concentration of intrathyroidal iodine (CII) in the most common units of measurement – mg/g or μg/g (used since 2016). If necessary, the conversion of some units of intrathyroidal iodine to others has the formula: CII (in μg/g) = ([density in HU] – 65) / 104. Based on the literature and our own research results, for the first time, we calculated the limits of normal intrathyroidal iodine fluctuations in euthyroid individuals, which are 85–140 HU units or 200–700 μg/g intrathyroidal iodine. Identification of the examined intrathyroidal iodine beyond the indicated fluctuations indicates the functional impairment of storing thyroid hormones, which ultimately will lead to hypothyroidism or hyperthyroidism (except when the patient is taking levothyroxine, mercazole, β-blockers – drugs that reduce intrathyroidal iodine). For the first time, an algorithm is presented for differential diagnosis of iodine-deficient and iodine-induced thyroid dysfunctions, which can only be done using CT: if there is a functional impairment of the thyroid gland with intrathyroidal iodinelevel less than 85 units of HU or 200 μg/g CII, then it is considered iodine deficient; with intrathyroidal iodinelevel more than 140 units of HU or 700 μg/g of CII, it is considered iodine-induced. The algorithm for the prevention of iodine-induced thyroid pathology with iodine prophylaxis is that iodine prophylaxis should not be prescribed or continued when intrathyroidal iodinelevel is 140 units of HU or 700 μg/g of CII or more.