Evaluation of endemic goiter prevalence in Bulgarian schoolchildren

Iodine deficiency is a major health problem worldwide. The environment of the Balkan countries, including Bulgaria, is distinguished for its low iodine content. In 1994, the strategies for the prevention and control of iodine-deficiency disorders were actualized in Bulgaria and universal salt iodization and supplementation for the risk population groups (schoolchildren, pregnant women) were introduced. The aim of this study was to assess the effectiveness of the iodine prophylaxis in schoolchildren, living in an endemic for goiter area after the introduction of salt iodization in Bulgaria. For this purpose, the goiter prevalence and iodine status in 483 schoolchildren (274 boys and 209 girls) aged between 8 and 15 yr, living in an endemic for goiter area in Bulgaria were evaluated. Despite the normalization of iodine supply, mild iodine deficiency on the basis of goiter prevalence (16.15%) and urinary iodine excretion was found. These data indicate the need for reevaluation of the national strategy for prevention of iodine deficiency.     

Anomalously low endemic goiter prevalence among Efe pygmies

The existence of endemic goiter, caused by iodine deficiency and the presence of a dietary goitrogen, has been noted in eastern Zaire by a number of authors (De Visscher et al.: Journal of Clinical Endocrinology and Metabolism 21:175-188, 1961; Delange et al.: Journal of Clinical Endocrinology and Metabolism 34:1059, 1972). In the Ituri Forest of Huate-Zaire, two distinct populations, the Efe (pygmy) and Lese (Bantu), live in association with each other and have similar diets. The goiter survey reported here documents differences in goiter prevalence and severity between the nomadic pygmy and village-living Bantu populations. While the Efe have an overall goiter prevalence of 9.4%, the Lese have a goiter prevalence of 42.9%. Furthermore, Efe women living in Lese villages and subsisting on a Lese diet have a prevalence of goiter similar to that of forest-living Efe women. Village-living individuals born of Efe mothers and Lese fathers have a prevalence of goiter greater than that of pure Efe but less than that of Lese. While our data cannot exclude dietary explanations for the difference in goiter prevalence between the Efe and Lese, they do support the hypothesis that the Efe possess an adaptation to an iodine-deficient environment that does not result in the development of goiters.     

Trace elements status in multinodular goiter

Importance of iodine and selenium in thyroid metabolism is well known, but the roles of other essential trace elements including copper, zinc, manganese and iron on thyroid hormone homeostasis remain unclear. The aim of this study was to investigate the status of those trace elements in benign thyroid diseases and evaluate possible links between trace element concentrations and thyroid hormones.The study group was composed of 25 patients with multinodular goiter. Concentrations of thyroid hormones (plasma-free thyroxine, FT₄; free triiodothyronine, FT₃; and thyrotropin, TSH), selenium, copper, zinc, manganese and iron in plasma, and urinary iodine were determined. The results were compared with those of a healthy control group (n=20) with no thyroid disorder.A mild iodine deficiency was observed in the patients with multinodular goiter whereas urinary iodine levels were in the range of “normal” values in healthy controls. All patients were euthyroid, and their thyroid hormone concentrations were not significantly different from the control group. Plasma selenium, zinc and iron concentrations did not differ from controls, while copper and manganese levels were found to be significantly higher in the patients with multinodular goiter indicating links between these trace elements and thyroid function and possibly in development of goiter. Besides iodine, there was a significant correlation between plasma copper concentration and FT₃/FT₄ ratio.     

Gender-specific determinants of goiter

Despite the strong implications of differences between females and males in the risk of goiter, gender-specific issues have not been extensively addressed in investigations of goiter prevalence. The objective of our analysis was to investigate the gender-specific determinants of goiter. Between April 2001 and April 2002. A total of 853 healthy employees from 4 institutions in the western part of Germany between 18 and 68 yr of age were examined by ultrasound of the neck to determine the thyroid volume. Information on sex, age, daily use of iodized salt, the history of goiter in the first-degree relatives, type and amount of smoking, oral contraceptives, and number of pregnancies were assessed by standardized questionnaires. Gender-specific predictors of goiter prevalence were assessed by multivariate logistic regression. The overall prevalence of goiter among study subjects was 204/853 (23.9%). Goiter was present in 80 out of 370 females (21.6%) vs 124/483 (25.7%) in males. In general, smoking (p<0.0001), increasing age (p<0.0001), and lack of daily intake of iodized salt (p=0.004) were associated with goiter prevalence, but not sex (p=0.39) and family history of goiter (p=0.16). In 370 females, parity (p=0.004) and lack of daily intake of iodized salt (p=0.01) were the major determinants for goiter, whereas age (p=0.18), oral contraceptives (p=0.82), family history of goiter (p=0.33), and smoking (p=0.09) did not affect goiter prevalence. In 483 males, smoking (p<0.0001) and age (p<0.001) affected goiter prevalence, but not family history of goiter (p=0.39), and the iodine status failed just to reach the significant level (p=0.08) in this analysis. Gender-specific determinants of goiter are parity and iodine status in females and smoking and increasing age in males.     

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.     

Epidemiologic examinations of goiter in the population of the Sejny community]

The study was aimed at the evaluation of incidence of goiter in the population of the community of Sejny. The survey comprising 1520 subjects revealed the presence of thyroid enlargement in 31.8% of the subjects studied, indicating the occurrence of a mild endemy. The facts speaking for this type of endemy are: predominance of cases with goiter of OB or I degree (83%), higher incidence of goiter in women than in men (3.3 times), occurrence of nodular goiter in 12% of cases with goiter, and sporadic appearance of hypothyroidism. Goiter endemy in the population of this area can be attributed to such goitrogenic factors as low level of iodine and high content of calcium in the water, tobacco smoking, and a habit of drinking tap water.     

History of endemic goiter in Croatia: from severe iodine deficiency to iodine sufficiency

At the time after the Second World War, endemic goiter was present in most parts of Croatia with a prevalence of more than 50% and presence of cretinism. In the village of Rude near Zagreb, goiter was detected in 85% of school children with 2.3% of cretins in the village population. In 1953 the first regulation on obligatory salt iodination, requiring 10 mg of potassium iodide (KI) per kg of salt was established in former Yugoslavia. A three-fold reduction of goiter prevalence, together with disappearance of cretinism was recorded ten years later In 1992, the National Committee for Eradication of Goiter was founded. The survey performed during 1991-1993 exhibited prevalence of goiter among school children between 8% and 35% and urinary iodine excretion under 10 microg/dL in most of the children from continental parts of the country. The new obligatory regulation, requiring 25 mg of KI/kg of salt, was proposed by the National Comittee and finally established in 1996. In 2002 thyroid volumes and medians of urinary iodine excretion were normal according to the ICCIDD criteria. Overall median of urinary iodine excretion for schoolchildren in Croatia was 14 ug/dL. Croatia crossed a path from severe iodine deficiency detected in the 1950's to the period of mild to moderate iodine deficiency during the 1990's, and finally, nowadays, iodine sufficiency has been achieved.     

Iodine and zinc, but not selenium and copper, deficiency exists in a male Turkish population with endemic goiter

Although endemic goiter has been shown to have a high prevalence in Turkey, little is known about the concentration of urinary iodine, plasma selenium (Se), copper (Cu), and zinc (Zn) in these patients. We studied on 140 male patient with endemic goiter (mean age: 22.2 ± 0.19 yr) and 140 healthy male subjects (mean age: 21.8 ± 0.28 yr). Daily urinary iodine excretion was determined by the ionometric method. Plasma Se, Zn, and Cu were determined by using atomic absorption spectrometry. Daily urinary iodine excretion was found to be significantly lower in the patient group (38.7 ± 2.26 μg/d) than that of controls (50.73 ± 2.56 μg/day,p = 0.001). Plasma Zn concentrations were also found to be significantly lower in the patient group (1.04 ± 0.03 μg/mL) than that of controls (1.16 ± 0.02 μg/mL,p = 0.001). No significant difference was determined in Se and Cu concentrations between the patient and control groups. Our study shows that a moderate iodine deficiency exists in both patients with endemic goiter and control subjects, which indicates the important role of iodine deficiency in the etiopathogenesis of endemic goiter in Turkey. Zinc deficiency may also contribute to the pathogenesis of endemic goiter. However, Se and Cu do not seem to have any role in the etiopathogenesis of endemic goiter in Turkey. A community-based iodine fortification program throughout the country may be proposed to take over the problem, which also can prevent the contributing effects of other element deficiencies that occur when iodine deficiency is the prevailing factor.     

Serum zinc levels and goiter in Iranian school children

Iodine deficiency has been shown to have high prevalence in Iran despite sufficient iodine supplementation. Zinc deficiency may also contribute to the pathogenesis of endemic goiter. The aim of this study was to compare serum zinc level in Iranian school children with and without goiter. A cross-sectional study was performed among urban children aged 8-12 years in city of Kerman, Iran. A multistage proportional to size cluster sampling method was used to screen 5500 subjects out of 29,787 students. After the screening phase, serum and urine specimens of randomly selected 165 students were evaluated for serum zinc levels and urinary iodine excretion and compared in goiterous and non-goiterous children. Serum zinc level was 149.5±29.4 μg/l in goiterous children and 141.2±52 μg/l in non-goiterous children but no significant difference was found between the groups (p=0.37). But urinary iodine excretion was significantly (p<0.001) lower in goiterous children (207.5 μg/l in goiterous children and 262.5 μg/l in non-goiterous children). This study showed that serum zinc level in goiterous and non-goiterus children is not different and zinc deficiency is not a risk factor for endemic goiter in this population.     

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.     

Hormone-containing peptides from normal and goiter human thyroglobulins

A series of low iodine human thyroglobulin samples derived from colloid-rich goiter tissue was examined by HPLC mapping of tryptic digests and compared to normal human thyroglobulin. These samples ranged in iodine content from 2 to 8 gram-atoms of iodine (g.a. I) per mole and were not further iodinated in vitro. Peptides containing the principal hormonogenic sequence were detected using the long wavelength absorbance of the iodotyrosine derivatives at 325 nm. Two such peptides were isolated and sequenced. Their thyroxine content was confirmed by radioimmunoassay. The number of 325-nm-absorbing peaks was significantly lower in the normally iodinated human thyroglobulin than that observed the thyroglobulins of cattle and dog. This suggests a more restricted iodination in the human protein. Sodium dodecyl sulfate gel patterns of the reduced and alkylated proteins showed significant molecular size heterogeneity in all of the samples. Polypeptide fragments ranged in molecular size from approximately 330 to 45 kDa in the goiter derived material and from approximately 330 to 15 kDa in the normal human material. This difference between the proteins is consistent with earlier observations that peptides less than 45 kDa appear concomitantly with hormone formation. These data confirm that the human thyroglobulin molecule is capable of forming at least limited amounts of thyroid hormone at iodine levels as low as 4 g.a. I per mole. The hormone detected in this study was located at residue 5 near the amino terminus of the thyroglobulin molecule.     

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.     

Metal-binding functions and antioxidant properties in human thyroid gland under iodine deficient nodular colloidal goiter

Copper and zinc levels in the tissue of thyroid gland (TG) and their metal-binding proteins metallothioneins (MT) as well as state of the antioxidant system in persons that had no thyroid disease and patients with endemic iodine deficiency nodular colloidal goiter has been investigated. In the patients with thyroid disease, oxidative damage was indicated despite elevated levels of MT-SH and glutathione, and elevated copper and decreased zinc concentration in TG tissue. MTs partly bound the excess of copper but its concentration in the unbound to MT form was two-fold compared to the control value.     

Endemic goiter, thiocyanate overload, and selenium status in school-age children

Iodine deficiency (ID) and related disorders are still major, yet unresolved health concerns. Recently, in a systematic survey of schoolage children (SAC), we reported severe to moderate ID, in Ankara and three cities from Black Sea region of Turkey. The current study attempted to evaluate selenium (Se) status, thiocyanate (SCN⁻) overload, and their possible contribution to the goiter endemics and thyroid hormone profile observed in these cities. Thyroid ultrasonography was performed and serum Se, SCN⁻, thyroid hormones, sensitive TSH (sTSH) levels, and urinary iodine concentrations (UICs) were determined from 251 SAC (9–11 yr old). Thyroid volumes (TVs) exceeding recommended upper normal limits and median UIC indicated goitre endemics and moderate to severe ID in the areas studied. Mean serum SCN⁻ concentrations were found to be greater than the controls from the literature. The UIC/SCN⁻ ratio was found to be lowest in Bayburt and Trabzon denoting that SCN⁻ overload may contribute to the goiter endemics. Serum Se concentrations represent a marginal deficiency in the four areas studied. No significant correlations between serum Se concentrations and the other parameters studied (i.e., TV, SCN⁻, thyroid hormones, sTSH, UIC) was detected. In conclusion, this study showed that selenium is also marginally deficient in the iodine-deficient endemic areas studied, but this has little or no impact on the thyroid hormone profile and the goiter endemics. SCN⁻ overload may contribute to the endemics, especially for the areas where iodine is severely deficient. An effective iodine supplementation program will not only resolve the goiter endemics but also the consequence of SCN⁻ overload as well in the endemic goiter areas studied.     

Familial nontoxic multinodular thyroid goiter locus maps to chromosome 14q but does not account for familial nonmedullary thyroid cancer.

Thyroid goiter is a common condition that is often associated with iodine deficiency. Familial forms of goiter in areas not known to feature iodine deficiency are much less common. We have performed a genomic search on a single large Canadian family with 18 cases of nontoxic multinodular goiter in which 2 individuals also had papillary lesions highly suggestive of papillary carcinoma. A locus on chromosome 14q (MNG1 [multinodular goiter 1]) has been identified, with a maximal two-point LOD score of 3.8 at D14S1030 and a multipoint LOD score of 4.88 at the same marker, defined by D14S1062 (upper boundary) and D14S267 (lower boundary). The gene encoding thyroid-stimulating hormone receptor (TSHR), which is located on chromosome 14q, is outside the linked region. To determine the role of this gene in familial nonmedullary thyroid cancer (NMTC), we studied 37 smaller pedigrees each containing at least two cases of NMTC. Analysis by both parametric and nonparametric methods indicates that only a very small proportion of familial NMTC (point estimate 0.001, support intervals 0-.6 under a dominant model) is attributable to MNG1.     

Low Iodine in the Follicular Lumen Caused by Cytoplasm Mis-localization of Sodium Iodide Symporter may Induce Nodular Goiter

Iodine is a key ingredient in the synthesis of thyroid hormones and also a major factor in the regulation of thyroid function. A local reduction of iodine content in follicular lumen leads to overexpression of local thyroid-stimulating hormone receptor (TSHr), which in turn excessively stimulates the regional thyroid tissue, and result in the formation of nodular goiter. In this study, we investigated the relationship between iodine content and sodium iodide symporter (NIS) expression by using the clinical specimens from patients with nodular goiter and explored the pathogenesis triggered by iodine deficiency in nodular goiter. In total, 28 patients were clinically histopathologically confirmed to have nodular goiter and the corresponding adjacent normal thyroid specimens were harvested simultaneously. Western blot and immunohistochemistry were performed to assay NIS expression and localization in thyrocytes of both nodular goiter and adjacent normal thyroid tissues. NIS expression mediated by iodine in follicular lumen was confirmed by follicular model in vitro. Meanwhile, radioscan with iodine-131were conducted on both nodular goiter and adjacent normal thyroid. Our data showed that NIS expression in nodular goiter was significantly higher than that in adjacent normal tissues, which was associated with low iodine in the follicular lumen. Abnormal localization of NIS and lower amount of radioactive iodine-131 were also found in nodular goiter. Our data implied that low iodine in the follicular lumen caused by cytoplasm mis-localization of NIS may induce nodular goiter.     

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 treatment of multinodular large non-toxic goiter using repeated doses of radioiodine (preliminary report)

INTRODUCTION: The aim of study was to establish the effectiveness of radioiodine therapy using 131I in the group of patients with multinodular large non-toxic goiter. MATERIAL AND METHODS: Therapy was undertaken in female patients disqualified from surgery due to high risk and these patients who didn't agree to surgery. Studies were performed in 7 women (age range: 62-82 yrs) with large goiters (2nd degree according to WHO classification and goiter volume assessed by USG over 100 cm(3)). Serum TSH, fT4, fT3, antithyroid antibodies (TPOAb, TgAb, TRAb) levels, urinary iodine concentration (UIE) were estimated in all patients parallel with radioiodine uptake test (after 5 and 24 hours), 131I thyroid scintigraphy and fine needle biopsy to exclude neoplasmatic transformation. These studies and therapy with 22 mCi 131I were repeated every 3 months. RESULTS: Before therapy median thyroid volume was approximately 145 cm(3) and during therapy gradually decreased to 76 cm(3) after 6 months and to 65 cm(3) after 12 months. Increase of TRAb can be a inhibiting factor of thyroid volume reduction. Other antithyroid antibodies showed marked tendency to rise but without significant correlation with radioiodine uptake and goiter reduction. After 12 months we found 2 patients with clinical and laboratory hypothyroidism. CONCLUSIONS: In some cases of multinodular large non-toxic goiter, the radioiodine therapy can be the best alternative way for L-thyroxine treatment or surgery therapy. The fractionated radioiodine therapy of multinodular large non-toxic goiter is safe and effective method but continuation of nodules observation is necessary.     

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.     

Insulin-like growth factor-I and insulin-like growth factor binding protein-3 levels of children living in an iodine- and selenium-deficient endemic goiter area

Serum insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-3 (IGFBP-3) levels were investigated in 31 children living in an endemic goiter area and 33 healthy subjects living in an nonendemic area. Serum IGF-I and IGFBP-3 levels of iodine- and selenium-deficient children were found to be lower than those of control subjects (p<0.001). There was a positive correlation between the IGF-I with chronological age and body mass index. There was also positive correlation between the IGF-I and IGFBP-3. No significant difference was found between the goitrous and nongoitrous children. These results suggest that IGF-I and IGFBP-3 levels are affected by thyroid dysfunction as a result of iodine and selenium deficiency. However, IGF-I and IGFBP-3 levels are not associated with goiter.