Iodine deficiency, more than cretinism and goiter

Recent reports of the World Health Organization show iodine deficiency to be a worldwide occurring health problem. As iodine status is based on median urinary iodine excretion, even in countries regarded as iodine sufficient, a considerable part of the population may be iodine deficient. Iodine is a key element in the synthesis of thyroid hormones and as a consequence, severe iodine deficiency results in hypothyroidism, goiter, and cretinism with the well known biochemical alterations. However, it is also known that iodine deficiency may give rise to clinical symptoms of hypothyroidism without abnormality of thyroid hormone values. This led us to the hypothesis that iodine deficiency may give rise to subtle impairment of thyroid function leading to clinical syndromes resembling hypothyroidism or diseases that have been associated with the occurrence of hypothyroidism. We describe several clinical conditions possibly linked to iodine deficiency, a connection that has not been made thus far. In this paper we will focus on the relationship between iodine deficiency and obesity, attention deficit hyperactivity disorder (ADHD), psychiatric disorders, fibromyalgia, and malignancies.     

Iodine deficiency and goiter prevalence of the adult population in Erzurum

It is believed that total goiter prevalence in Turkey is as high as 30.5%. The iodine deficiency is the distinct etiologic factor in the development of goiter. The aim of this study was to determine goiter prevalence and iodine deficiency in adults living in Erzurum (1659 m above sea level) for at least 10 year. The study involved 340 people (192 females, 148 males). The median age was 38.5 year (ranging from 20 to 76 years). Ultrasound-measured thyroid volume (TV) for men (TV>25 ml) and for women (TV>18 ml) was considered goiter indicator. By this evaluation, goiter was diagnosed in 94 (27.6 %) cases, whereas the goiter prevalence, based on the palpation method, was 5.6%. Urinary iodine concentration (UIC) was measured by ammonium persulfate method. UIC in subjects with goiter was significantly lower than that of the others (median values 5.0 vs 7.8 microg/dl, p<0.0001). While the value of UIC > or = 10 microg/dl (no. 121, 36.6%) was accepted normal, the extent of iodine deficiency in other subjects was classified as severe (UIC<2.0 microg/dl, no.53, 15.6%), moderate (UIC=2.0-4.9 microg/dl, no.75, 22%) and mild (UIC=5.0-9.9 microg/dl, no.91, 26.8%). TV values were found to be significantly different among the four groups (p<0.05). TV values were significantly correlated with body surface area and UIC (r=0.15 and r=-0.16, respectively, p<0.005). Also, the prevalence of thyroid nodules was estimated as 2.1% by palpation and 18% by ultrasonography. We conclude that goiter originating from iodine deficiency has been an important health problem in Erzurum. Besides taking measures at national level, local factors and risks which interfere with the nationwide efforts should also be dealt with for the eradication of the iodine deficiency problem. In the region, periodical evaluation of iodine level and iodine related disorders will guide the measures to be taken for the well being of people's general health.     

Iodine vs thyroxine. A changing concept of therapy in endemic goiter?

Summary The hypothesis that goitrogenesis in iodine deficiency can be attributed to the stimulatory effect of thyrotropin (TSH) on the thyroid gland and has long been held to be valid. The task of this review is to describe the reasons why this concept is being challenged. In addition, we report on the autoregulation of the thyroid gland and on in vitro investigations dealing with TSH as a growth factor, which have yielded conflicting results. Finally, we summarize preliminary studies comparing the therapeutic effect of thyroxine and iodine on goiter size. In comparison to thyroxine, iodine application in doses of 300–500 µg/day may represent an equally effective way of treatment in areas of endemic goiter, especially in younger patients. In this age group, the risk of side-effects, e.g., iodine-induced thyrotoxicosis, should be low.Abbreviations DIT Diiodotyrosine - FT₄I Index for free thyroxine - KI Potassium iodide - TSH Thyrotropin - TRH Thyrotropin releasing hormone - T₄ Thyroxine - T₃ Triiodothyronine     

Pathomorphism of endemic goiter

Pathomorphism of goiter developing against the background of goiter prevention in the Bukovina endemic area was studied. Subdivision of goiter into endemic and sporadic lost its significance due to the stabilization and levelling of the goiter morbidity. The true (simple or benign) goiter is characterized by an euthyroid course, predominant affection of adult women and domination of the nodular variants. A goiter node is a hyperplastic structural-functional gland unit--the thyron. The leading role in the goiter etiology belongs to endogenous deficiency of thyroid hormones, local factors are significant in the goiter pathogenesis.     

Immunological features of endemic goiter

Some immune aspects of simple endemic goiter have been studied through a comparison of IgG, IgA, IgM, kappa and lambda chains, and C3 and C4 in the peripheral blood of 59 patients operated on for goiter and the peripheral blood of 49 normal controls. The median IgM was lower in the goiter blood. The incidence of thyroglobulin (Tg) and microsomal (Mi) antibodies (Abs) was 20.3% in goiter blood and that of nonthyroid autoAbs was 37%. Active and total rosetted blood lymphocytes were counted and OKT3, OKT4, OKT8, Leu 1, Leu3a, Leu2b, T DR+, and NK cell populations were classified. Helper T cells were occasionally decreased when goiter was associated with lymphocytic thyroiditis. The NK percentage was sometimes higher in goiter blood, whereas the T DR+ percentage was not significantly different in the two groups. Lymphocyte infiltration (LI) was noted in 32% of goiters (about 5% with a diffuse and nodular pattern). A prevalence of helper/inducer cells was observed among the infiltrating T cells. HLA-DR antigen (Ag) positive epithelial cells were seen, not only in LI areas. Granular deposits of IgG, IgA, IgM, and C3 on the follicular basal membrane were stained in 6.7% of goiters Patterns histologically and immunologically similar to those in Hashimoto's thyroiditis may therefore be observed in long-standing simple endemic goiter, suggesting that an autoimmune mechanism may be involved in its pathogenesis.     

Hand skeletal development among Ecuadorians living under conditions of iodine deficiency and endemic goiter.

Hand radiographic assessment has revealed the pattern of skeletal growth and maturation among Ecuadorian Indian villagers where iodine deficiency has resulted in an endemia of goiter and cretinism. This is intended to provide base line information for future attempts to learn about physical impairment among people living under inadequate iodine nutriture.     

Iodine deficiency in the Russian Federation

Epidemiological surveys for iodine deficiency (ID) were made in 30 regions of Russia in 1992 to 1999. A total of 40,999 individuals aged 7 to 17 years were examined. The advent of new assessments of the thyroid and new indicators of iodine deficiency has changed approaches to epidemiological surveys. The WHO standards for estimating the prevalence and severity of ID have been introduced into Russian practice. In Central Russia, the lowest (median 30-58 micrograms/l) iodine concentrations were found in rural dwellers; in more urbanized areas (cities, towns) the median was 50-78 micrograms/l. ID was more pronounced in the regions of East Russia where it was predominantly moderate (median 30-52 micrograms/l). In some areas, ID was severe (median 16-20 micrograms/l). As the severity of ID increases, the incidence of such conditions, as goiter, hypothyroidism, endemic cretinism is on the rise. Mild to moderate goiter endemia prevailed in Central Russia. The manifestations of goiter endemia were more pronounced in rural children (18-30%) than in urban ones (8-14%). East Russia was marked by moderate to severe goiter endemia (8-14%): the incidence of goiter ranged from 17 to 40%. There were only sporadic cases of goiter in some areas of the Sakhalin Region. In the Moscow and Voronezh Regions and the Republic of Kalmykia there were areas showing a high goiter incidence which did not correspond to the level of ID. An epidemiological analysis has indicated that dietary and water iodine intake is decreased in most regions of Russia. The actual dietary iodine intake was 40-80 micrograms/day, i.e. 2-3 times of the recommended allowance (150 micrograms). The Endocrinology Research Center has tested different models of preventive and therapeutical measures for eliminating iodine deficiency-caused diseases by using iodinated foodstuffs (salt, bread, butter) ad iodine medicaments.     

Frequency of medullary thyroid carcinoma in an endemic goiter area

A series of 41 poorly differentiated follicular carcinomas of the thyroid gland without histopathological features of medullary or papillary carcinoma and 9 cases of undifferentiated thyroid carcinoma of the small cell type (diagnosed between 1967 and 1983) were investigated immunohistochemically. Two poorly differentiated follicular carcinomas showed a considerable number of calcitonin-positive cells in addition to the weakly thyroglobulin-positive tumor cells. One of these cases revealed several areas with calcitonin-positive tumor cells with additional squamous metaplasia with keratinization. No medullary carcinomas could be demonstrated among the 9 cases previously diagnosed as undifferentiated thyroid carcinomas of the small cell type. From the epidemiological point of view the application of immunohistochemistry does not significantly increase the proportion of medullary carcinomas detected in our endemic goiter area. The incidence of medullary carcinoma remains surprisingly low when compared with nonendemic areas.     

狨猴地方性甲状腺肿动物模型的复制

在 1 90 7～ 1 90 8年 ,Ｍａｒｉｎ用羊、猪、狗、牛复制了饲以低碘饲料所致的动物模型[1 ] 。阐明了碘和甲状腺肿的关系 ,证实碘缺乏可造成甲状腺的胶样肿和增殖。此后 ,有人分别用大鼠、鸡、小鼠、兔复制了低碘动物模型。动物模型的重要性取决于它和人类罹患疾病条件的相关性。已证实碘缺乏在各种种属致病的重要性是一致的。然而 ,各种动物模型都有它的优点和局限性。学者们多采用羊和大鼠。羊体型较大 ,适于孕期研究 ,便于施行手术[2 ] ,但其胎盘结构不同于大鼠及人类。大鼠来源方便 ,价格便宜 ,但由于碘需要量低 ,复制碘缺乏比羊困难。…     

Neurological disorders and endemic goiter: comparative analysis of 2 provinces in Togo

Neurological diseases are one of the main causes of high mortality and morbidity in developing countries. The prevention of these diseases is possible if they are well known. The purpose of this study was to evaluate the prevalence and the distribution of the main neurological affections in two rural districts. WHO research protocol for measuring the prevalence of neurological disorders in developing countries was used by the same staff. The first survey was conducted in Kloto from July to August 1989 on 19,241 inhabitants and the second in Akébou from January to February 1995 on 4182 subjects. Akébou was known as endemic goiter district. The prevalence of epilepsy was 12.3@1000 in Kloto and 13.1@1000 in Akébou. That of stroke was 2.4@1000 in Kloto versus 1.7@1000 in Akébou. The prevalence of Parkinson's disease was 0.2@1000 in Kloto and 0.2@1000 in Akébou. That of psychomotor retardation was 3.2@1000 in Kloto versus 8.1@1000 in Akébou. The prevalence of neurological cretinism was 97@1000 while that of myxoedematous cretinism was 31@1000 in Akébou. Apart from neurological disease, the prevalence of goitre was 43% in females and 26.1% in males in Akébou. Mental retardation and cretinism were frequent in Akébou, a district endemic for goitre. Besides stroke and febrile convulsions which predominated in Kloto, the main neurological disorders were most prevalent in Akébou. Community based care for epilepsy is provided in these districts as is the prevention of iodine deficiency in the Akébou district with the intention of reducing neurological affections.