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The main causes of simple diffuse goiter (SDG) and multinodular goiter (MNG) are iodine deficiency, increase in serum thyroid-stimulating hormone (TSH) level, natural goitrogens, smoking, chronic malnutrition, and lack of selenium, iron, and zinc. Increasing evidence suggests that heredity is equally important. Treatment of SDG and MNG still focuses on L-thyroxine-suppressive therapy surgery. Radioiodine alone or preceded by recombinant human TSH stimulation is widely used in Europe and other countries. Each of these therapeutic options has advantages and disadvantages, with acute and long-term side effects.

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BACKGROUND: We have demonstrated that the administration of delta-iodolactone (i.e., 5-iodo-delta lactone) of arachidonic acid (IL-delta), a mediator in thyroid autoregulation, prevents goiter induction by methylmercaptoimidazol (MMI) in rats. Other studies have shown that transforming growth factor beta-1 (TGF-beta1) mimics some of the actions of excess iodide, but its participation in autoregulation is disputed. The present studies were performed to test the hypotheses that IL-delta decreases thyroid growth by inhibition of cell proliferation and/or by stimulation of apoptosis due to oxidative stress, that TGF-beta is stimulated by an excess of iodide and by IL-delta, and that c-Myc and c-Fos expression are upregulated during goiter induction and downregulated during goiter inhibition. METHODS: Rats were treated with MMI alone or together with iodide or IL-delta. Thyroid weight, cell number, cell proliferation, apoptosis, and oxidative stress were determined. Proliferating cell nuclear antigen (PCNA), TGF-beta1, TGF-beta3, c-Myc, and c-Fos were measured by Western blot. RESULTS: MMI caused a progressive increase in thyroid weight accompanied by an increase in cell number, asymmetry of the ploidy histograms, and PCNA, c-Fos, and c-Myc expression. In addition, an early increase of apoptosis was observed. Peroxides as well as glutathione peroxidase and catalase activities were also increased in goitrous animals. The inhibitory action of IL-delta on goiter formation was accompanied by the inhibition of cell proliferation evidenced by a significant decrease in cell number, PCNA expression, and asymmetry of the ploidy histograms. A transient stimulation of apoptosis after 7 days of treatment was also observed. MMI administration stimulated TGF-beta1 but not TGF-beta3 synthesis. IL-delta alone caused a slight increase of TGF-beta3 but not TGF-beta1, whereas potassium iodide (KI) stimulated both isoforms and MMI reversed KI effect on TGF-beta1 expression but not on TGF-beta3. CONCLUSIONS: The goiter inhibitory action of IL-delta is due to the inhibition of cell proliferation and the transient stimulation of apoptosis. This latter action does not involve oxidative stress. TGF-beta1 does not play a role in the autoregulatory pathway mediated by IL-delta. Iodide stimulates TGF-beta3 without the need of being organified. These results suggest that there may be more than one pathway involved in the autoregulatory mechanism.

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INTRODUCTION: Thyroid autoregulation has been related to intraglandular content of an unknown putative iodocompound. The thyroid is capable of producing different iodolipids such as 6-iodo-deltalactone (ILdelta) and 2-iodohexadecanal (2-IHDA). Data from different laboratories have shown that these iodolipids inhibit several thyroid parameters. ILdelta has an antigoitrogenic action but no data about the action of 2-IHDA on this parameter has been published. OBJECTIVES: to study the action of 2-IHDA on methimazole (MMI)-induced goiter and analyze if this compound can cause the involution of preformed goiter. RESULTS: Administration of MMI to rats during 10 days increased thyroid weight by 112%. This effect was significantly inhibited by the simultaneous injection of 20mug/day of 2-IHDA (51% vs. MMI) while iodine or non iodinated hexadecanal were without action. Thyroidal proliferating cell nuclear antigen (PCNA) content was increased by MMI while 2-IHDA decreased this value (control: 100%; MMI: 190+/-11; MMI+2-IHDA: 134+/-10). Serum TSH was increased after MMI administration and 2-IHDA did not modify this parameter (control: 1.89+/-0.10; MMI: 8.19+/-0.93ng/ml; MMI+2-IHDA: 7.38+/-0.72). Treatment with MMI increased thyroidal cAMP content (control: 16.1+/-0.82, MMI: 42.4+/-4.6 fmol/mg protein) while injection of 2-IHDA significantly decreased this value (22.3+/-2.0). Goiter prevention by 2-IHDA was also observed at 30 days of treatment reducing total number of cells (51% inhibition) and epithelial height (81% inhibition). Goiter involution was induced after withdrawal of MMI and injection with 2-IHDA, KI or saline. 2-IHDA led to a reduction of 74.5% in thyroid weight after 3 days while spontaneous involution (saline) was only of 32%. KI failed to alter this value. This significant involution was accompanied by a reduction in the number of cells (66%). Administration of the iodolipids did not produce significant changes in several serum parameters such as total T(3) and T(4), cholesterol, transaminases, urea and creatinine. CONCLUSION: 2-Iodohexadecanal, as 6-iodo-deltalactone, prevents goiter growth in rats and opens a potential therapeutic application of iodolipids.

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El déficit de yodo (IDD) es un problema de la Salud Pública que afecta a millones de personas en todo el mundo y es causante de alteraciones en la neuromaduración que pueden ser evitados si se realiza una yodoprofilaxis adecuada. Objetivo: Realizar un monitoreo de IDD en la localidad de Wanda, provincia de Misiones, por su ubicación geográfica y hábitos alimentarios con posible consumo regional de sal no iodada. Se estudiaron en 502 escolares de 5 a 14 años de vida , se evaluaron: peso, talla , BMI y palpación tiroidea. En 114 de ellos se determinó la yoduria en muestras casuales de orina. Se analizaron los niveles de TSH de la pesquisa neonatal de los 18 meses previos al estudio, realizados por métodos sensibles (IFMA-DELFIA). Se aplicaron los criterios de suficiencia establecidos por la OMS/ ICCDD. Resultados: La prevalencia de bocio en la región fue de 6.2 %. Los niveles de yoduria tuvieron una mediana de 239 ug/l. El valor de TSH neonatal mediano fue 1.25 uU/ml. Sólo el 1.4 % de las muestras estaban por encima de 5 uU/ml . Cuando se aplicaron los criterios de la OMS pudo observarse que la prevalencia de bocio superaba levemente lo esperado para una zona suficiente, pero no así los niveles de ioduria ni la distribución de TSH neonatal. Conclusión: El aporte iodado de la región evaluada es suficiente como lo demuestran la ioduria y los niveles de TSH neonatal. La presencia de bociógenos como la mandioca en la dieta puede explicar el leve aumento en la prevalencia de bocio. La utilización de la pesquisa neonatal de hipotiroidismo congénito en la supervisión de la deficiencia de yodo añade un beneficio al objetivo primario que es la prevención del retraso mental.

O b j e c t i v e : To estimate the adequacy of iodide intake in Wanda Misiones through the conventional parameters of ioduria and goiter prevalence in scholars as well as with the distribution of TSH neonatal levels as performed for the hypothyroidism screening program in newborns. Population and methods: Height , and BMI and weight were assessed in 502 scholars aged 5 to 14 and expressed as SDS. In 419 of them (215 female) thyro i d volume was evaluated and classified according to WHO (9). In 114 children iodide urinary concentration was measured in casual urine samples by Sandell y Kolthof method modified by Pino (17). Neonatal screening program for congenital hypothyroidism is carried out in the region measuring TSH in filter paper samples with IFMA DELFIA. Since 2000 7.102 newborn have been screened. TSH level's distribution of the 18 months prior to this study (n 267) were evaluated. Criteria suggested by WHO to indicate iodide deficiency were applied. Results: Height, weight and BMI were normal for the chronological age according to Argentinean population parameters. Goitre prevalence was 6.2 % (7.3 % in girls and 5.3 % in boys), higher that expected for a iodide sufficient area. Iodide urine median levels were 239 ug/l with a distribution that excluded iodide deficiency. Neonatal screening program detected 5 congenital hypothyroid children out of the 7102 newborn studied. All of them were early and adequately treated. Only 1.4 % of the 267 samples were > 5 µU/ml, excluding iodide deficiency. Conclusion: Iodide intake in Wanda, Misiones, is adequate as shown by the findings of iodide urine concentration and TSH neonatal levels. A higher prevalence of goitre than expected for this situation, could be explained by dietary intake of goitrogen food as mandioca. Congenital hypothyroidism screening program in this region was extremely effective. The possibility of using its results for iodide intake supervision is an additional benefit to the one of early prevention of mental retardation.

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Se denomina bocio al aumento de tamaño de la glándula tiroidea, que da lugar a un abultamiento en la región anterior del cuello, el agrandamiento de los lóbulos laterales de la tiroides debe ser superior al tamaño de la falange distal del dedo pulgar del paciente. La tiroiditis de Hashimoto es la inflamación crónica de la tiroides de origen autoinmunitario; cursa con bocio y puede provocar hipotiroidismo existe un hipotiroidismo, este se desarrolla en forma paulatina. El tratamiento del paciente hipotiroideo consiste en la administración de levotiroxina.

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3,5,3'-triiodothyroacetic acid (TRIAC) has been used to suppress pituitary TSH secretion with reported attenuation of extrapituitary effects. We investigated whether equivalent doses of T (3) and TRIAC preventing the induction of goiter by methimazole (MMI) had a different or similar impact on peripheral tissues, such as liver and bone. In particular, we compared the effects of both compounds on the activity of the hepatic thyroid hormone-responsive enzymes, malic enzyme and L-glicerol-3-P dehydrogenase; bone mineral density and biochemical parameters of bone turnover, such as bone alkaline phosphatase (b-ALP) and the carboxy-terminal telopeptide region of type I collagen (beta-CTX); and the activity of thyroid ornithine decarboxylase (ODC). We also compared the effects of T (3) and TRIAC on the involution of MMI-induced goiter. Our results showed that TRIAC was more effective than T (3) to reduce MMI-induced goiter in a short-term goiter involution assay. TRIAC increased hepatic enzymes activity and beta-CTX levels, a parameter of bone resorption, more than T (3). However, bone mineral density was not altered by either treatment. Both compounds even reduced ODC activity at doses that were not effective at the pituitary level. These results demonstrate increased TRIAC hepatic and antigoitrogenic activity compared to T (3). TRIAC induces an imbalance in bone remodeling without affecting bone mineral density. Further studies are required to clarify this point.

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Os fatores associados à recidiva de bócio pós-tiroidectomia por doença benigna da tiróoide ainda näo estäo completamente definidos, especialmente o uso profilático de hormônio tiroidiano. Objetivo. Determinar a prevalência, características e fatores associados à recorrência de bócio em pacientes submetidos à tiroidectomia por doença benigna. Métodos. Foram incluídos 66 pacientes, 53 mulheres e 13 homens (idade média = 51 anos, variaçäo = 20-82 anos) submetidos previamente (5,6 + or - 1 anos) à tiroidectomia (lobectomia, n = 50; nodulectomia, n = 5; tiroidectomia subtotal, n = 11). Na ocasiäo do estudo foi realizada ecografia de tiróide e dosagens séricas de T3, T4, TSH e anticorpos antimicrossomal. Definiu-se como recorrência de bócio a presença de volume residual >20mL e/ou novos nódulos >0,5mL à ecografia e näo previamente detectados durante a cirurgia. Resultados. SEte pacientes (10 por cento) apresentaram recorrência de bócio. O tempo de acompanhamento foi mais longo no grupo com recorrência (p < 0,5) e näo foi observada diferença em relaçäo a idade, sexo presença de história familiar de tiropatia e diagnóstico pré-operatório entre os dois grupos. Na análise de regressäo múltipla, apenas o tmepo de acompanhamento pós-tiroidectomia foi significativamente associado à recorrência de bócio (ß = 0,02;//2 = 0,16; p < 0,05), influenciando em 14 por cento a taxa de recorrência. História familiar de tiropatia, uso de hormônio tiroidiano e níveis séricos de T4 e TSE näo influenciaram a recorrência. Conclusäo. A recorrência de bócio pós-tiroidectomia por doença benigna de tiróide ocorre numa minoria de pacientes e estáa relacionada com o maior tempo de acompanhamento após a cirurgia. O uso de hormônio tiroidiano em doses näo supressiva após a cirurgia näo se relaciona à prevençäo de recorrência

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The factors associated with post-thyroidectomy goiter recurrence in benign thyroid disease are not clearly defined, especially prophylactic thyroxine treatment. PURPOSE--To determine the prevalence, characteristics and associated factors of recurrence of goiter post-thyroidectomy in patients submitted to surgery for benign disease. METHODS--Sixty-six patients, 53 female and 13 male (mean age = 51 yrs., range 20-82 yrs.), previously (5.6 +/- 6.1 yrs.) submitted to thyroidectomy (lobectomy, n = 50; nodulectomy, n = 5; subtotal thyroidectomy, n = 11) for benign thyroid disease were included. Measurements of T3, T4, TSH, thyroid microsomal autoantibody titers and thyroid ultrasonography were performed at the time of the study. Recurrence of goiter post-thyroidectomy was defined on ultrasonography as the presence of residual thyroid volume > 20mL and/or new nodules > 0.5mL not detected at surgery. RESULTS--Seven patients (10%) developed recurrence of goiter. The post-operative follow-up period was longer in the recurrence group and there was no difference between the two groups as to age, sex, familial history of thyropathy and preoperative goiter diagnosis. In multiple regression analysis only the following post-operative period was significantly associated to goiter recurrence (beta = 0.02; R2 = 0.16; p < 0.05) and influenced the goiter recurrence rate by 14%. Familial history of thyropathy, thyroxine treatment in non-supressible doses after thyroidectomy and seric T4 and TSH levels did not influence the recurrence. CONCLUSION--Recurrence of goiter post-thyroidectomy occurs in a small number of patients and is related to longer post-operative follow-up time. Thyroxine treatment in non-supressible doses after surgery is not related to goiter recurrence prevention.

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The thyroid gland synthesizes 6-delta-iodolactone, a compound shown to inhibit goiter growth in vivo and cell proliferation in culture. The present studies were performed to characterize this effect further with the aim of exploring the possible therapeutic action of iodolactones. Prevention assay: rats were treated simultaneously with a goitrogen, methylmercaptoimidazole, and either 6-delta-iodo-lactone or 14-iodo-omega-lactone, a synthetic derivative, given either i.p. or p. o. Both compounds caused a significant decrease in thyroid weight irrespective of the route of administration, but oral administration was less effective. A dose-response relationship was observed, the minimal effective dose (i.p.) being 3 micrograms/day. Involution assay: goiter was first induced with methylmercaptoimidazole and then the iodolactones were injected. Both compounds caused a significant involution, which was dose-related. Acute (10 days) administration of the iodolactones did not produce significant changes in several serum parameters (total T3 and T4, cholesterol, total protein, urea and acetylcholinesterase). These results give further support to the potential therapeutic application of iodolactones.

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Cancer of the thyroid accounts for less than 1% of all cancers recognised each year, but the incidence is rising. Much of the early work of the epidemiology and aetiology of thyroid cancer was based on the assumption that thyroid cancer can be treated as an entity. The recognition that two distinct types of endocrine cell occur within the thyroid has made it clear that any discussion of the aetiology and epidemiology of thyroid malignancies must take into account the histological classification of these tumours. Moreover, there are difficult problems to be considered when comparing thyroid cancer incidence across tumour registries, because of a lack of standardisation or morbidity data collection, difficulties in histological diagnosis, varying rates of diagnosis of occult papillary carcinoma, and prevalence and techniques of autopsies. So far only a relatively small proportion of thyroid cancer cases can be explained with adequate certainty as regards epidemiology and aetiology. As in cancer in general, the aetiology and epidemiology of thyroid cancer in detail remains unknown in the majority of cases.

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El motivo fundamental es la de estimar la magnitud de la deficiencia del yodo y de los desórdenes producidos por la deficiencia del yodo (DDI). De acuerdo a una encuesta realizada en 1981 por el Instituto Nacional de Alimentación y Nutrición estableció que el 60.8 por ciento, el departamento más afectado es Chuquisaca con el 74 por ciento y el menos afectado el departamento de Pando con 43 por ciento. Por otra parte la información disponible en PRONALCOBO se puede afirmar que la prevalencia de los desórdenes por deficiencia del yodo en el país es inferior a 5 por ciento

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