Results of studies on the effect of radiologic contamination after the Czernobyl catastrophe and prophylactic iodine on thyroid morphology and function of inhabitants of North-East Poland]

The results of the investigations of radioactive contamination after the Chernobyl catastrophe and subsequent iodine prophylaxis on the thyroid gland function and morphology in Northeast Poland. The aim of the study was to determine whether kalium iodine in one dose during radioactive contamination in Poland limited the radioactive dose in the thyroid gland and if significant disadvantageous side-effects in the intrathyroid and extrathyroid occurred. Additionally during the studies we tried to determine if radioactive iodine contamination which occurred in the region of the Medical Academy in Bia?ystok caused an increase in thyroid disease. It is interesting to note the different results obtained after radioactive contamination with the results from the investigations in this same territory in 1983-1985. In 1983-1985, before the Chernobyl catastrophe, 6,921 persons in Northeast Poland were investigated. In 1986-1988, immediately after the disaster 4,010 persons were investigated. The main study according to grant No MZ-XVII was carried out in three provinces: Bia?ystok, Suwa?ki and Olsztyn. In this investigation 10,011 persons born before April 26, 1986 and after January 1, 1936 participated, 5,789 townspeople and 4,222 villagers, 3,987 children up to 16 years of age it the time of the disaster 1,973 boys and 2,009 girls; 6,024 adults 2,509 men and 3,516 women were drawn from a register. Committed doses to the thyroid in the investigated region were one of the highest in Poland and depended on age group and were depended on time of prophylaxis non proportional. Iodine prophylaxis was provided mainly with one dose of Lugol solution about 90%, 95% children and 30% adults took iodine. The majority of the population (53.3%-74%) were given iodine in April. From May 1st to 5th 23.0-43.4% received iodine, but after May 5th very few persons. Iodine was well tolerated, but Lugol Solution was better tolerated than other kinds of iodine. Only 241 (4.4%) cases had side effects, mainly vomiting (143), symptoms such as stomach ache, diarrhea, dyspnoe, skinrash etc. in lesser numbers. 12% (29 persons) were seen by a physician. In the investigated population were 200 pregnant women aged 19-40 years of which the majority (177) delivered full term healthy babies. Only 1 interrupted pregnancy and 7 had spontaneous abortion. Changes in the thyroid were noticed by 187 persons (2.3%-11.7%) most of which were enlargement of the thyroid, but only a few were confirmed by a physician. In the studied population from 1989 to 1990 over 30% of the population had struma.(ABSTRACT TRUNCATED AT 400 WORDS)     

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.     

Data from the Wroc?aw region about thyroid diseases and use of prophylactic iodine after the reactor accident in Czernobyl]

The radiological contamination of Wroc?aw Region after Czernobyl accident was evaluated as moderate. In the frame of Research Programme MZ-XVII 4310 persons (2012 men and 2298 women) were randomly selected and investigated. Among them were 1525 children up to 16 years old. 925 children and 854 adults took potassium iodide; only minority in April but majority between May 1st and May 5th. Side effects was rare phenomenon seen in about 5% of those who ingested potassium iodide and in majority of cases was very mild (with rash and vomiting as most common clinical symptoms). Only 13 persons with side effects have visited physicians. Among 955 women aged 19-40 years 71 were pregnant in May 1986. 55 of them delivered on time, 3 before time. Average health state of newborns was 9.1 according to Apgar scale. 10 women have had spontaneous abortion and 3 decided to terminate pregnancy in first 6 weeks. The physical examination revealed the presence of diffuse goiter in 384 persons and of nodular goiter in 23 persons. In majority of cases the goiter was small, OB or I. according to WHO classification.     

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.     

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.     

Epidemiologic studies after the disaster in Czernobyl in the population of children in the Krakow region]

In 1989-1990 the epidemiologic studies about the impact of of Czarnobyl events on the health of children in Kraków and Nowy Sacz region were performed. The morphologic and functional changes of thyroid gland in children were estimated. Almost 90% of children in both districts received the iodine preparations for prophylactic reason. The mean time of intake was between 5-10 days following the Czarnobyl explosion. There were no relationship between the dose of iodine absorbed during prophylactic action and incidence of goiter. The prevalence of goiter amounted to 34.8-47.6% in boys and girls consecutively in Kraków district and 53.8-70.5% in Nowy Sacz. No hormonal changes in T3, T4 and TSH serum concentration were found in children with goiter and those without goiter. The complications after iodine intake were transient and seen only in a small number of children.     

Role of Bamboo-Shoot in the Pathogenesis of Endemic Goiter in Manipur,North East India

ObjectiveEndemic goiter is prevalent in the iodine-sufficient region of Manipur, India. Bamboo shoot (BS), a goitrogenic plant food, are consumed regularly in the area. The objective of this study was to examine the role of BS in the pathogenesis of endemic goiter.MethodsGoiter prevalence, urinary iodine, and thiocyanate (SCN) excretion in school children, iodine content in drinking water, and the household consumption of salt fortified with iodine were measured. To confirm the goitrogenic potential of BS, its progoitrogenic constituents were fed to rats as part of an iodine-sufficient diet, after which the animals' thyroid gland morphology and functional status were assessed.ResultsGoiter prevalence was 31% in 4852 children, and the median urinary I and SCN levels were 176.3 μg/L and 0.962 ± 0.190 mg/dL, respectively. Of the households assessed, 90% consumed salt fortified with adequate iodine. Progoitrogenic constituents were high in BS from Manipur. Increased thyroid weight, hypertrophy and hyperplasia of follicular cells, decreased thyroid peroxidase activity, and low serum thyroxine (T₄) and triiodothyronine (T₃) levels were observed in BS-fed rats.ConclusionNearly one third of the studied participants had palpable goiter, despite a successful salt iodine fortification program. SCN from BS causes goiter in iodine-sufficient experimental animals. Similar ingestion in study participants was confirmed and is the likely cause for the persistence of endemic goiter in the Manipur region. (Endocr Pract. 2013;19:36-45)     

Results of a cytogenetic study of children from radionuclide-contaminated goiter endemic zone of the Rivno region of Ukraine

Under the conventional cytogenetical examination of 6 different children groups (with and without non-stohastic thyroid pathology, exposed and nonexposed to the iodine isotopes in 1986) from the goiter endemic zone of Ukraine which belongs to the territory contaminated by 137Cs radionuclides, the identical to the spontaneous level of somatic chromosome mutagenesis of the last decade in all observed groups with the tendency to increasing of stable aberrations in some persons had been established.     

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.     

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.     

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.     

Iodized oil as a complement to iodized salt in schoolchildren in endemic goiter in Romania

OBJECTIVE: To evaluate the long-term efficacy and possible side effects of low doses of iodized oil on iodine nutrition and thyroid function in endemic goiter in Romania. METHODS: Random selection of 214 schoolchildren aged 6-14 years. Serial measurements of urinary iodine, thyroid volume with ultrasound, serum concentrations of thyrotropin, free thyroxine, thyroglobulin and thyroid autoantibodies before and up to 2 years after the oral administration of 200 mg iodine in iodized oil. RESULTS: Urinary iodine concentrations indicated a moderate iodine deficiency before therapy, sharply increased soon after therapy and slowly decreased thereafter but remained within the normal range up to more than 1 year after therapy. The prevalence of goiter was 29% before the administration of iodized oil and 9% 1 year later. Thyroid function tests and autoantibodies were normal before and up to 2 years after therapy. CONCLUSION: A single dose of 200 mg iodine from oral Lipiodol appears adequate and safe for correcting moderate iodine deficiency in children.     

Results of studies performed with the MZ-XVII program on a national scale; summary and conclusions]

MOST IMPORTANT OBSERVATIONS: (FROM COUNTRY-WIDE POPULATION STUDIES) 1. In some voivodships localized in south-east and north-east parts of Poland thyroids of young children would, without protective measures, accumulate more then 60 MsV of radioiodine, thus exceeding intervention level settled for the country. 2. Thyroid function of newborns exposed to radioiodine during neonatal life was normal and frequency of neonatal hypothyroidism similar to that seen in years before Czernobyl accident. 3. Potassium iodide administrated to newborns in some of them profuced transient rise of TSH (Wolff-Chaikoff phenomenon), thus suggesting, that ki dose settled for newborns could be to high. 4. Thyroid radioiodine dose accumulated in thyroids of older children, teenagers and adults was in majority of regions well below the dose of 50 MsV. 5. The frequency of non-toxic diffuse goiter, especially in traditional endemic goiter area was found to be high, but is also relatively high in others regions of Poland and seems to depend on iodine deficiency or relative iodine deficiency. 6. The frequency of other thyroid disorders is within the limit reported in countries with relative iodine deficiency. 7. More than 95% of children and teenagers took protective, single dose of potassium iodide (about 10 millions). 8. Approximately 27% of adults took protective dose of potassium iodide (about 7 millions). 9. Organization of protective action in 11 north-east and south-east voivodoships was good about 75% of all obtain ki solution within 24 hours. In the rest of the country where protective action was ordered april 30, in afternoon hrs only about 25% obtained ki the same day and the rest during next 48-72 hrs. 10. The fact that prior to the protective action limited number of children was given iodine alcohol solution permitted for external use speaks about the fear and panic observed in Poland in first days after Czernobyl accident. 11. Extrathyroidal side-effects after ki administration appeared in about 5% were usually light or moderate and in majority of cases disappearing without medical assistance. Vomiting was most commonly seen side-effect in young children, thus suggesting that either dose, or the chemical form of the drug for this group of age was unproper. 12. Intrathyroidal side-effects of single dose of ki was rare phenomenon seen mostly in newborns, very young children and some adults with history of thyroid disease in the past. 13. Its possible that even small dose of radioiodine accumulated in thyroid produce immunological response leading to the appearance of thyroid antibodies in blood serum.     

Iodine toxicity and its amelioration

Iodine (I) toxicity is rare in animals and humans, but nuclear explosions that give off radioactive I and excessive stable I ingestion in parts of the world where seaweed is consumed represent specialized I toxicity concerns. Chronic overconsumption of I reduces organic binding of I by the thyroid gland, which results in hypothyroidism and goiter. Bromine can replace I on position 5 of both T(3) and T(4) with no loss of thyroid hormone activity. Avian work has also demonstrated that oral bromide salts can reverse the malaise and growth depressions caused by high doses of I (as KI) added as supplements to the diet. Newborn infants by virtue of having immature thyroid glands are most susceptible to I toxicity, whether of stable or radioactive origin. For the latter, the 1986 Chernobyl nuclear accident in Belarus has provided evidence that KI blockage therapy for exposed individuals 18 years of age and younger is effective in minimizing the development of thyroid cancer. Whether bromide therapy has a place in I toxicity situations remains to be determined.     

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.     

Thyroid cancer incidence among liquidators of the Chernobyl accident

The increase of thyroid cancer incidence rate among children living in the Chernobyl contaminated territories of Belarus, Russia and Ukraine has widely been accepted. Our current work deals with thyroid cancer incidence in the cohort of liquidators (99024 persons) living in 6 regions of Russia: North-West, Volgo-Vyatsky, Central-Chernozemny, Povolzhsky, North-Caucasus and Urals. In the period 1986-1998, a total of 58 thyroid cancer cases were detected in this cohort. We found a statistically significant increase of the thyroid cancer incidence rate in liquidators as compared to the baseline (male population of Russia) level (SIR=4.33, 95% CI: 3.29; 5.60). It was demonstrated that there is no dependence of incidence rates due to external radiation exposure (ERR/Gy=-2.23, 95% CI: -4.67; 0.22).     

Low serum selenium concentration as a possible factor for persistent goiter in Iranian school children

Selenium deficiency can have adverse effect on thyroid metabolism and response to iodine supplementation. The aim of this study was to determine relationship between prevalence of goiter, thyroid hormone profile, urinary iodine and serum selenium concentrations in Iranian schoolchildren. In a cross- sectional study, 1188 schoolchildren in the age group of 8-13 years were evaluated for goiter prevalence. Urine and serum samples were collected from 500 children and assayed for urinary iodine concentration, thyroid hormone profile and serum selenium concentration. The overall goiter prevalence was 39.6% and the median urinary iodine excretion, indicated to an adequate iodine intake. The mean serum selenium concentration was 119.1 +/- 31 mug/l with significant difference between boys and girls (108.4 +/- 26.2 mug/l vs 127.7 +/- 32.1 mug/l). An increase in free T4 concentration was observed in those with a lower selenium level and there was a significant relationship between the presence or absence of goiter and serum selenium concentration. Selenium supplementation may be an advisable measure to optimize thyroid hormone metabolism and decrease the prevalence of goiter in schoolchildren with low serum selenium concentration.     

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.     

Chronicled report on the period from May 1 to September 27, 1989. Discussion of risk factors]

The Institute of Mother and Child was invited in 1988 by professor J. Nauman to his Chernobyl program, so as to inspect children born after Chernobyl accident, particularly these born in first days following the accident dated 26 april 1986. The central part of Poland is covered with screening for congenital PKU and hypothyroidism therefore all children had estimated TSH-spot levels between 3rd and 5th day of life. So as to control the present state of general health and thyroid state in the study group a questionnaire with a letter to parents explaining the aim of the inquiry was sent to the parents (see addenda). About 14000 letters were send from which around 12000 responses were returned to the Institute. From informations received this way we draw the preliminary conclusion that no significant damage in health of these children or their siblings can be found. About 20% of the mothers admitted taking the Lugol solution in a last day of pregnancy. However it should be taken into account that these data were collected 2 years after the accident and are not fully reliable. In the period 1989-1990 a group of 1912 children (938 boys and 974 girls) was called to the Department of Endocrinology of the Institute and inspected. The age was from 2.9 to 4.2 years. All children had screening TSH-spot test result negative (below 30 microIU/ml). General health state The general health state of the children inspected was good. Only 33 of them (1.7%) had various congenital malformations what is not different from general population of polish children. Mental development was in 1897 cases normal, in 15 cases IQ was decreased and the score varied from 75 to 80 according the Brunet-Lezine scale. Average physical development was normal. Body height evaluated in standard deviation score (SDS) was as follows: SDS = 0.0 in 359; SDS = +0.9 +/- 0.6 in 906 and SDS = -0.5 +/- 0.3 in 647 cases. Thyroid state At 1904 inspected and analytically estimated children the thyroid function was normal. Only in 8 cases (0.8%) a goiter was found with euthyroid state. Analytical data were as follows: total T4 serum level = 111.8 + 43.1 nmol/l (50.4-171.9), ref. value: 50.1-170.0 nmol/l; total T3 serum level = 2.5 +/- 0.4 nmol/l (ref. value 1.9-3.6); TSH serum level 4.4 +/- 2.6 uIU/ml. Trace amounts of antithyroid membrane antibodies were found at 12 children (0.63%) of the group in serum diluted 1:250.(ABSTRACT TRUNCATED AT 400 WORDS)