Influence of radioactive contamination and iodine prophylaxis after the Czernobyl disaster on thyroid morphology and function of the Poznan region]

The radioactive contamination of Poznań Region was recognized after Chernobyl accident as average. The predicted values of minimal (inhalation) and maximal (inhalation and ingestion) committed dose equivalent to the thyroid varied from 2.5 (min) to 24.7 (max) mSv in different groups of adults and children. To follow up the results of iodine prophylaxis and some aspects of possible thyroid gland morphological and functional changes 11086 persons were carefully investigated clinically and biochemically. Among these 11086 persons were 42.6% males and 57.4% females both adults from 17 till 40 year and children up do 16 years. The following parameters were reviewed: pregnancy, time of residence in the region, thyroid abnormalities, family history concerning thyroid diseases, iodine intake in April and May 1986 with possible side effects, changes in the thyroid size observed before and after 1986, degree and kind of thyroid enlargement, serum concentration of T3, T4, TSH, ATMA and ATG titre and finally the effectiveness of thyroid blockade at 24, 48 and 72 h after ingestion of Lugol's solution. Side effects of the ingestion of potassium iodide from 30-70 mg were observed in 153 cases, 36 of them consulted medical doctors but in no case the side effects (dominated by vomiting) threatened the life. In the investigated group were 144 pregnant women. Majority, because 88% of them delivered the baby on or after time and 6.9% before time, 4.9% of natural abortions were noted but non artificial. In the group of children thyroid gland abnormalities before 1986 were reported in 3 cases in 23 after 1986 it is after Chernobyl accident. This information is interesting but needs more precise analysis of different dependencies occurring. The data obtained indicated the existence in Poznań. Region the goiter endemy because 27.5% of investigated children and adults had goiter classified as grades O-B, I, II and III. The elevation or diminution of T3 values were noted in 1164 cases, for T4 in 418 cases and for TSH in 1412 cases. The presence of antimembrane and antithyroglobulin antibodies were observed in 303 cases. All persons with changes observed in thyroid morphology and function are periodically controlled and the results will be published separately. The investigations performed and results presented concern the early aspects of radioactive contamination and effects of iodine prophylaxis. The answer regarding late effects including thyroid cancer needs further multi year studies for which the clinical material investigated in different parts of Poland and well documented should be used as model group for further periodical studies.     

Antithyroid autoantibodies in the examined population with iodine prophylaxis after the Chernobyl catastrophe

The aim of the present study was the observation of the frequency of antithyroid autoantibodies in the population in low endemic goitre area after mass iodine prophylaxis after the Chernobyl catastrophe and the estimation of TSH and thyroid hormones secretion in this population. On the basis of the investigations carried out we could conclude that the frequency of antithyroid autoantibodies in the population with confirmed endemic goitre is comparable to the frequency of antithyroid autoantibodies in the healthy population. ATA occurrence in children after iodine prophylaxis could confirm the hypothesis that thyroglobulin immunity is higher after iodine intake. The lower T3 concentration observed in the group with antithyroid autoantibodies suggests that autoantibodies may be involved in the thyroid hormones synthesis or peripheral conversion of thyroid hormones.     

Effectiveness of iodine prophylaxis and frequency of thyroid enlargement (thyroid goiter) and clinical diagnosis of thyroid diseases in inhabitants of the Szczecin region after the Czernobyl accident]

The study, supported by program MZ-XVII, was carried on 4567 inhabitants of the area of Szczecin (2350 females and 2217 males). The population was chosen randomly, according to a simple drawing scheme. All subjects were clinically examined using standardised questionnaires. In 3468 persons (including 1807 girls and women, 1661 boys and men) apart form clinical examination, the assessment of thyrotropin, thyroxine and triiodothyronine in serum and frequency of antithyroglobulin antibodies and antithyroid membrane antibodies were evaluated. The data indicate that 94% of children in Szczecin's region received the prophylactic dose of iodine, mostly between the 1st and the 5th of May 1986. Only 17% of the adults received iodine. The most common preparation was Lugol solution given in a single dose. Among all persons who received iodine, only in 5% of subjects the side effects were noted (mostly in children), including symptoms of gastrointestinal tract (vomiting, abdomen pain) and occasionally intrathyroid side effects (thyroid pains). In examined population the high frequency of thyroid enlargement, mainly in women (up to 43-44% at the age group 30-50 years) was found. The frequency of clinical diagnosis of thyroid disease was higher in women than in man (most often the diffuse goiter, rarely the nodular goiter). The frequency of thyroid enlargement and clinical diagnosis of thyroid disease was not dependent on prophylactic iodine intake. The iodine prophylaxis did not influence on thyroid hormones and TSH serum levels and on frequency of antithyroid antibodies.     

Iodine deficiency in pregnancy--a continuing public health problem

Iodine prophylaxis in Poland started in 1997 and is based on mandatory iodzation of household salt with 20-40 mg KI/ 1 kg, supplementation of bottle fed infants with iodized formulas with 10,0 microg KI/100 ml, and a voluntary supplementation of pregnant and breast feeding women with additional 100-150 microg of iodine/ day. Last evaluation of efficacy of the iodine prophylaxis performed in 2003 by WHO and International Council for the Control of Iodine Deficiency Disorders allocated Poland within the group of the European countries with sufficient iodine supplementation on the population level. However according to data of the Institute of Mather and Chield in Poland, around 50 % of pregnant women only is additionally supplemented with iodine. Iodine deficiency during pregnancy even as a moderate iodine deficiency, creates a risk of mental retardation, perinatal complication like low and very low births weigt of neonates with increased perinatal mortality rate and late consequences in adult life: metabolic syndrom and type 2 diabetes. Another limitation of the actual model of iodine prophylaxis in Poland, it is too high consumption of natrum chloride (over 5,0 g of household salt/day/ capita). It is around 50% over WHO recommendation. Intensive preventive program against hypertension, type 2 diabetes, atherosclerosis, osteoporosis and some neoplasmatic diseases includes limitation of natrum chloride consumption- as one of the risk factors. Therefore new scope of the National Programme for Elimination of Iodine Deficiency will include: a special prorgramme for the iodization of animal food according to european standard, increased rate of pregnant women additionally supplemented with iodine, strengthening public awarness on necessary increase of milk consumption especially in pregnancy and in children and continouse monitoring system of biologic effects and technologic quality of the model of iodine prophylaxis.     

Erratum to Central European Journal of Biology, Volume 8, Issue 12

Paper by Bogdan Jaroszewicz, Ewa Piro?nikow, Marcin Churski “Vegetation diversity influences endozoochoric seed dispersal by moose (Alces alces L.)“ in Voulme 8, Issue 12, 1250-1264/ December 2013; DOI: 10.2478/s11535-013-0244-3 contains incorrect affiliations of Ewa Piro?nikow and Marcin Churski. Ewa Pi?niow works in Institute of Biology, University of Bia?ystok, 15-950 Bia?ystok, Poland; while Marcin Churski works in Mammal Research Institute, Polish Academy of Sciences, 17–230 Bia?owie?a, Poland.     

Relationship between thyroid size and urinary concentration of iodine in the population of Bialystok]

The survey carried out in May 1991 in the city of Bia?ystok comprised 308 children of age between 8 and 14 years and 116 young adults. In each of the studied subjects the size of the thyroid was measured by ultrasonography and iodine concentration determined in a randomly voided sample of urine. Body weight and height of the subjects have also been measured. In about 50% of the subjects studied (58.4% of children, 38.5% of men and 58.4% of women) the presence of goiter accompanied by a low urinary iodine concentration (median--2.0 micrograms/ml) was found. A significant negative correlation between the thyroid size and urinary iodine concentration, and lack of relation between the former and TSH concentration, have been found. No relation was observed between the presence of goiter and the inadequate physical development in the children studied. Insignificantly elevated TSH levels without accompanying clinical symptoms of hypothyreosis were observed in 8.7% of children, 3.8% of women and 5.1% of men studied. Higher prevalence of goiter found as compared to the results previously obtained in the same area can be related on the one to the use of more precise methods and on the other to real worsening of the situation due to discontinuation of obligatory iodine prophylaxis in the country more than 10 years ago.     

Work of the Polish Council for Control of Iodine Deficiency Disorders, and the model of iodine prophylaxis in Poland

The Polish Council for Control of Iodine Deficiency Disorders (PCCIDD) was established in 1991 in Krakow at the Chair and Dept. of Endocrinology, Jagiellonian University, Collegium Medicum, following the example of the International Council for Control of Iodine Deficiency Disorders (ICCIDD) in Charlottesville, USA. The PCCIDD co-operates with the European Co-ordinating Centre in Pisa, Italy. The PCCIDD comprises a group of experts in endocrinology, iodine prophylaxis, the technology of salt and food iodisation, and Polish representatives of several organisations: WHO, UNICEF, the Polish Consumers Federation, and the Spokesman for Children's Rights. The strategic goal of the Polish Council is to solve the problem of iodine deficiency in Poland realising the Programme for Elimination of Iodine Deficiency financed by the Ministry of Health. The Polish model of iodine prophylaxis contains obligatory iodisation of household salt (20-40 mg KI/1 kg) and neonates' formula (10 μg/100 mL of milk), and additional supplementation for pregnant and breastfeeding women with 150-200 μg of iodine as pharmacotherapy. The model is very effective: endemic goitre in schoolchildren has been eradicated, the prevalence of goitre in pregnant women has fallen from 80% to 19%, the frequency of transient hypothyroidism in neonates has dropped from 2.0% to 0.16%, and the observed increase of incidence rate of thyroid cancer in women over 40 years old has diminished markedly. In 2008, a WHO Collaborating Centre (WHOCC) for Nutrition was designated at the Department of Endocrinology, UJCM in Krakow. The main goal of the WHOCC is to sustain effective iodine prophylaxis in Poland in the light of the latest WHO recommendations on the necessary reduction of daily salt intake as a risk factor for hypertension and arteriosclerosis. Therefore, additional standardised carriers of iodine (milk, mineral water) have been introduced into the food market.     

Occurrence of infections with C burnetii (Q fever) in persons from increased risk groups in Poland--serological survey and evaluation of studied methods]

During years 1988-1991 at Regional Sanitary and Epidemiological Stations in Bia?ystok, Kielce, Lublin, Leszno, Piotrków Trybunalski, Lód?, Poznań, Plock, Opole, Sanok, Skierniewice and Zielona Góra--serological studies in persons amenable to compulsory check-up against brucellosis were performed for detection of infections with C. burnetii. In whole, 20651 persons were investigated on the Polish territory and it was found that in 22.8% antibodies against antigens of C. burnetii are present. Percentage of persons with detected antibodies varied in different regions from 0 to 41.7%. No antibodies were found in persons inhabiting regions of Kielce, Piotrków Trybunalski and Skierniewice. Most persons with antibodies indicating contact with C. burnetii were found in West Poland, namely in the Leszno and Poznań region. As in diagnosis of Q fever two methods (OWD and OMA) or OWD only were applied, it is difficult to compare results obtained in regions using two or only one method of determination.     

Epidemiologic foundation for population studies of program MZ-XVII]

Epidemiological foundation included: aim of studies, knowledge about epidemiology of thyroid disorders in Poland, evaluation of radioiodine dose accumulated in thyroids of inhabitants of different age living in different par of Poland, information about relative diet iodine deficiency in different parts of Poland and identification of research teams (manpower) capable to carry on population studies. The final identification of epidemiological foundation was proceeded by pilot studies performed in 4 different regions of Poland. Finally it was decided that population studies would be performed in so called Regions of 6 different University Medical Schools (Bia?ystok, Kraków, Lód?, Poznań, Szczecin, Wroc?aw). The sample will be selected randomly on the base of information from the voting lists (random selection of vovoidoship, then towns and villages, then streets and number of houses, then number of flats. All living in selected flat or house during Czernobyl accident and born between January 1974 and December 1985 (children) and between January 1926 and December 1973 (adults) will be considered "the sample". In all cases the sample will be examined by means of unified questionnaire and protocol of medical and laboratory examination. The same kits (of the same producers) will be used to evaluate serum TSH, T4, T3 and thyroid autoantibodies. The data obtained will be evaluated by unified computerized system. Separate studies involved the sample of newborns exposed to radioiodine during last trimester of pregnancy, found to be euthyroid and given potassium iodide in first days of life. Separate system was also used to investigate effect of radioiodine and of prophylactic dose of potassium iodide in those with past history of thyroid disorders.     

Thyroid cancer incidence in Ukraine: trends with reference to the Chernobyl accident

For the first time, a comparative analysis of thyroid cancer incidence in Ukraine after the Chernobyl accident was done in a cohort that is almost as large as the general population. On the basis of thyroid doses from radioactive iodine in individuals aged 1-18 years at the time of accident, geographic regions of Ukraine with low and high average accumulated thyroid doses were established and designated "low-exposure" and "high-exposure" territories, respectively. A significant difference of thyroid cancer incidence rates as a function of time between the two territories was found. That is, the increase in the incidence was higher in high-exposure regions than in low-exposure regions. The incidence rates varied substantially among the different attained age-groups, especially in the youngest one (up to 19 years old). The analysis that was adjusted for screening and technological effects also indicated that in the high-exposure regions, thyroid cancer incidence rates at the age of diagnosis of 5-9, 10-14 and 15-19 years were significantly higher in those born in 1982-1986 compared to those born in 1987-1991, while in the low-exposure regions, no significant difference was observed. The observed probable excess of radiation-induced thyroid cancer cases in adults exposed to radioactive iodine from the Chernobyl accident, especially in females, may be due to the high power of the present study. However, it should be noted that our investigation was not essentially free from ecological biases.     

Epidemiology of thyroid diseases in the population of the Sejny community after the atomic catastrophe in Chernobyl]

The survey carried out in 1990 covering the population of Sejny community, sponsored by the Ministry of Health and Welfare, program MZXVII, demonstrated the occurrence of goiter in 33.6% of studied persons. Such an incidence can rightly be recognized as an endemy. Predominance of cases with small or moderate enlargement of the thyroid (OB and I), low percentage of nodules (18%), and 2.8 times more frequent occurrence of goiter in women allows o characterize the endemy as mild. The percentage of goiter in this population does not differ from that found in this area before the Chernobyl disaster. However a small increase in the incidence of thyroid enlargement in a group of boys of age between 17 and 19 years, and an increase in percentage of nodular goiter in whole population was noted. The questionnaire studies confirmed in addition a high effectiveness of mass iodine prophylaxis introduced after the atomic disaster, especially in the population of developmental age. However, because of the latency period concerning the possible effects, the results obtained will be verified in the course of long-term prospective studies.     

Evaluation of equivalent body burden in the thyroid for the people of Poland on results of 131I absorption after the disaster in Czernobyl. Determination of thyroid blockade with potassium iodide]

An assessment of effectiveness of the administering of single dose of stable iodine in Poland on the reduction of 131I doses in thyroid has been performed. 5-compartment model of metabolism of iodine developed by Johnson has been used to evaluate predicted levels of stable iodine and 131I content in thyroid and commitment dose equivalent H50 for different doses of stable iodine and various age and sex group population. The measured values of 131I concentration in air and in milk and standard values for milk and food consumption and inhalation rate as well as metabolic parameters were used. Theoretical calculations showed that administering of stable iodine on 1986-04-28, 1986-04-29, 1986-04-30 and 1986-05-01 could have reduced committed dose equivalent H50 form ingestion with inhalation pathway by about 44%, 40%, 26%, 12% respectively. On the basis of measured 131I activity in the thyroid for inhabitants from different districts in Poland (1400 measurement) committed dose equivalents were determined and analysis of radiation hazard from 131I were performed. In the most contaminated regions of Poland average H50 doses for children 1-5 and 5-10 years old are close to 50 mSv (permissible level for population) and maximal doses exceed this limit four times. These maximal doses occurred for about from 5% inhabitants from these area. In the moderate and low contaminated regions of Poland the average doses are fivefold and tenfold less respectively.     

Karyopathological traits of thyrocytes and exposure to radioiodines in Belarusian children and adolescents following the accident at the Chernobyl nuclear power plant

The Belarus-American (BelAm) thyroid study cohort consists of persons who were 0-18 years of age at the time of exposure to radioactive iodine fallout from the 1986 Chernobyl nuclear power plant accident and who have undergone serial thyroid screenings with referral for fine-needle aspiration biopsy (FNAB) using standardized criteria. We investigated thyrocyte nuclear abnormalities in cytological samples from FNABs in 75 BelAm subjects with single and multiple thyroid nodules and 47 nodular goiter patients from Leningrad, Russia, unexposed to Chernobyl fallout. Nuclear abnormalities examined included internuclear chromosome bridges and derivative nuclei with broken bridges (i.e., "tailed" nuclei), which are formed from dicentric and ring chromosomes and thus may be cellular markers of radiation exposure. Among subjects with single-nodular goiter, thyrocytes with bridges were present in 86.8% of the exposed BelAm cohort compared with 27.0% of unexposed controls. The average frequency of thyrocytes with bridges and with tailed nuclei was also significantly higher in the BelAm subjects than in controls. Among subjects with multinodular goiters, thyrocytes with bridges were present in 75.7% of exposed BelAm patients compared with 16.7% of unexposed controls; thyrocytes with tailed nuclei were observed in all of the BelAm subjects but in only 40% of controls, and the mean frequencies of bridges and tailed nuclei were significantly higher in the exposed group. Unusually, long bridges were detected in 29% of BelAm patients with single-nodular goiters and 35% of those with multinodular goiters, while no such abnormalities were observed among patients from the Leningrad region. In the exposed subjects from BelAm, we also found positive correlations between their estimated dose of Iodine-131 from Chernobyl fallout and the frequency of tailed nuclei (p = 0.008) and bridges (p = 0.09). Further study is needed to confirm that these phenomena represent consequences of radiation exposure in the human organism.     

Iodine concentration in the blood and urine in children depending on the goiter size

Epidemiological investigations have shown that at the Bia?ystok Province about 30% of children and youth is afflicted with goitre. In this area drinking water is poor in iodine and iodine supply with food is quite unsatisfactory. The purpose of the present work has been to check the behaviour of the serum and urine iodine in children with thyroid goitre. The estimations of I in blood serum were made in 126 children with goitre (I, II, and III, according to the WHO classification) and in 100 healthy children. The method used included buthanol extraction according to Fisher and Morris. The concentration of iodine and its excretion rate in urine were assessed in 119 children with goitre of various advancement, an; in 170 children not affected with goitre, using the method of Fisher and Morris adopted to urine analysis. The authors found the following values for serum protein bound iodine: control group 4.9 microgram/100 ml, at average; 4.3 microgram/100 ml, 3.0 microgram/100 ml, and 2.6 microgram/100 ml in those affected with I, II, and III of the goitre, respectively. The 24 hr urine excretion rate of iodine in healthy children amounted to 66.4 microgram, and 64.2 microgram, 53.6 microgram, and 4o.2 microgram in those with I, II, and III goitre, respectively. The above results indicate a significant decrease of iodine concentration in blood serum and in urine in children with goitre; this decrease has been found to be dependent on the degree of the thyroid gland enlargement. The differences were statistically significant.     

The effect of Chernobyl accident on the development of malignant diseases--situation after 20 years

The accident that occurred at the Chernobyl Nuclear Power Plant in 1986, released large quantities of radionuclides--among them radioiodine--into the atmosphere, thereby raising public concerns about its influence on thyroid structure and function, especially the development of malignancy. There were even reports about 700 deaths due to thyroid carcinoma in Russian Federation, Ukraine and Belarus, resulting from the accident. In this review we discussed the incidence of thyroid cancer in different parts of the world, especially in heavily contaminated countries, as Ukraine and Belarus, and the possible link between radioisotope activity in the thyroid and the development of malignancy. The study carried out in Minsk showed 40-fold increase of the incidence of thyroid cancer in the years 1986-1994, in comparison to the period 1977-1985. An increase of the incidence of thyroid cancer has generally been observed in many countries after the Chernobyl accident. We focused on the factors that may have an influence on this phenomenon, especially diagnostic tests, health care, social and environmental factors, like iodine level in water and soil. The results of molecular biology studies, e.g. RET translocation in carcinoma type RET/PTC1 in elderly and RET/PTC3 in children, and expression Ax1 and Gas6 in children were reviewed as well. We also mentioned other thyroid diseases, like nodular goitre, cysts, the disturbance of thyroid function and autoimmunity, possibly linked to the radiation after Chernobyl accident. Data obtained from the regions near Chernobyl showed no increased risk of other types of malignancy (leukaemia, Hodgkin's and non Hodgkin's lymphoma) in 1986-1996. In this article the epidemiology of thyroid diseases in Poland was also reviewed.     

Results of epidemiologic studies performed after the disaster in Czernobyl among the adult part of the population in the region of Krakow]

Epidemiologic studies following the Czernobyl accident were performed in region Kraków, including Kraków, Nowy Sacz and Kielce district. 1426 males and 2495 females were selected according to the random sample on the whole population of Kraków and Nowy Sacz, as well as in some selected areas in Swietokrzyski Mountains, and in Kielcecity. The aim of the study was to assess the results of the prophylaxis with Kalium iodine after the radiation and the incidence of the goiter in the population. It was stated, that 19.2% of the population in Kraków district, 16.9% in Nowy Sacz and 20% in Kielce received the prophylactic dosis of K.J. 80% took mainly the Lugol solution, between May, the 1st and 5th, 1986. Among 18 of person showing side effects like gastrointestinal disturbances, 16 were of female sex. Goiter incidence according to WHO classification was 50.7%, 67.3% and 49.9% in Kraków, Nowy Sacz and Kielce respectively. The difference between the incidence of goiter in males and females was 1:3. In women it was rather Ist and IInd degree of goiter, in men OB and Ist. Nodules of thyroid gland in the rural region of Kraków, Nowy Sacz and Kielce were seen in women in 10.8%, 1.7%, add 12.3% consecutively. Hormonal studies i.e T3, T4, TSH serum concentration showed normal results in all groups studied. TSH concentration was the highest in the group OB. The microsomal and antithyroglobulin antibodies level was the same independently on the prophylactic dosis of Lugol solution. The high incidence of thyroid diseases not related to the accident was observed.(ABSTRACT TRUNCATED AT 250 WORDS)     

The experimental optimization of iodine prophylaxis for decreasing the radiation load from the accidental uptake of radioiodine]

As is proved by nuclear disaster in Chernobyl Nuclear Power Plant (NPP), iodine prophylaxis may be respected as one of the most urgent and effective methods of prevention of radiation injury of the thyroid gland in the population affected. Author has studied factors and methods of its efficacy and reliability. On the basis of experiments in rats, analytical ways of determination of the dietary iodine intake (iodine supply) of people living around NPP Paks (Hungary) as well as compartment modelling, experiments it is shown, that for optimisation of iodine prophylaxis in masses it is very important to increase the iodine supply up to the recommended values. Combined use of decreased doses of potassium iodide and perchlorate was found to be the optimal way for removal of radioiodine from pregnant organisms and their offsprings following accidental intake of radioiodine.     

Evaluation of iodine levels in daily dietary intake and urine of persons participating in epidemiological studies in the Krakow macro-region after the disaster in Czernobyl and level of iodine in drinking water of that region]

Following the Czernobyl accident, an epidemiologic study was undertaken in which the daily iodine intake was estimated in 15% of the population studied. Iodine excretion was measured in single morning urine specimens. The iodine content was also assessed in the water form wells and in cow-milk at farms in randomly chosen villages in the region of Krynica and Nowy Sacz. On the basis of a 24-hour diet recall, the mass of each food product consumed daily was estimated for 483 persons in the Kraków voivodship (14.4% of the total population) and for 397 persons in the Nowy Sacz voivodship (15.8% of the total population). Using this data, the nutrient content of the daily diet was calculated for each studied individual. Measurements of iodine content in water and cow-milk show relatively lower iodine levels in the Nowy Sacz voivodship. The estimated value of the iodine content in milk (5.5 micrograms/100 g of milk) was considered in the estimates of the chemical composition of the daily diet of the inhabitants of this region. The mean values of the daily energy as well as the protein and calcium consumption in all subpopulations grouped with respect to domicile, age and sex, fell within the recommended daily allowances for these groups. The iodine content, while widely scattered, concentrated around low values. The median values of the iodine content in children of age 3-10 years, age 10-16 years and in adults, were 66%, 48% and 25-40% of the recommended daily allowances, respectively. No particular differences in the food intakes were observed between inhabitants of Kraków and Nowy Sacz voivodships. Nor were significant differences found in the urine iodine excretion in groups of these regions. The low iodine content in the daily food intake may be an essential factor in the ethiology of the increasing number of thyroid goiter.     

The role of iodine in human growth and development

Iodine is an essential component of the hormones produced by the thyroid gland. Thyroid hormones, and therefore iodine, are essential for mammalian life. Iodine deficiency is a major public health problem; globally, it is estimated that two billion individuals have an insufficient iodine intake. Although goiter is the most visible sequelae of iodine deficiency, the major impact of hypothyroidism due to iodine deficiency is impaired neurodevelopment, particularly early in life. In the fetal brain, inadequate thyroid hormone impairs myelination, cell migration, differentiation and maturation. Moderate-to-severe iodine deficiency during pregnancy increases rates of spontaneous abortion, reduces birth weight, and increases infant mortality. Offspring of deficient mothers are at high risk for cognitive disability, with cretinism being the most severe manifestation. It remains unclear if development of the offspring is affected by mild maternal iodine deficiency. Moderate-to-severe iodine deficiency during childhood reduces somatic growth. Correction of mild-to-moderate iodine deficiency in primary school aged children improves cognitive and motor function. Iodine prophylaxis of deficient populations with periodic monitoring is an extremely cost effective approach to reduce the substantial adverse effects of iodine deficiency throughout the life cycle.     

Association of Iodine and Iron with Thyroid Function

Iodine and iron are essential elements for healthy thyroid function. However, little is known about the association of iron and iodine with thyroid function in the general US population. We investigated iron and iodine status in relation to concentrations of thyroid hormones. We included 7672 participants aged 20 and older from three surveys (2007–2008, 2009–2010, and 2011–2012) of the National Health and Nutrition Examination Survey. Serum thyroid measures (including free and total T3 and T4, and TSH), serum iron concentration, and urinary iodine concentrations were measured. Multivariate linear regression models were conducted with serum thyroid measures as dependent variables and combinations of serum iron concentration and urinary iodine concentration as predictors with covariate adjustment. Logistic regression models were performed with TSH levels (low, normal, and high) and combinations of serum iron concentration and urinary iodine concentration. Overall, 10.9% of the study population had low iron; 32.2 and 18.8% had low or high iodine levels, respectively. Compared with normal levels of iron and iodine, normal iron and high iodine were associated with reduced free T3 and increased risk of abnormal high TSH. Combined low iron and low iodine was associated with reduced free T3 and increased TSH. In addition, high iodine was associated with increased risk of abnormal high TSH in females but not in males. Thyroid function may be disrupted by low levels of iron or abnormal iodine, and relationships are complex and sex-specific. Large prospective studies are needed to understand the mechanisms by which iron interacts with iodine on thyroid function.