Eduardo Pretell

Recommendations of the Latin American Thyroid Society on diagnosis and management of differentiated thyroid cancer.

The aims of these recommendations were to develop clinical guidelines for evaluation and management of patients with differentiated thyroid cancer applicable to Latin American countries. The panel was composed by 13 members of the Latin American Thyroid Society (LATS) involved with research and management of thyroid cancer from different medical centers in Latin America. The recommendations were produced on the basis of the expert opinion of the panel with use of principles of Evidence-Based Medicine. Following a group meeting, a first draft based on evidences and the expert opinions of the panel was elaborated and, later, circulated among panel members, for further revision. After, this document was submitted to the LATS members, for commentaries and considerations, and, finally, revised and refined by the authors. The final recommendations presented in this paper represent the state of the art on management of differentiated thyroid cancer applied to all Latin American countries.

Iodine Nutrition Improves in Latin America

Iodine deficiency has been a public health problem in most Latin American countries. Massive programs of salt iodization have achieved great progress toward its elimination but no consistent monitoring has been applied. We used the ThyroMobil model to visit 163 sites in 13 countries and assess randomly selected schoolchildren of both genders 6-12 years of age. The median urinary iodine concentration (8208 samples) varied from 72 to 540 microg/L. One national median was below the recommended range of 100-200 microg/L; five were 100-200 microg/L, and seven were higher than 200 microg/L, including three greter than 300 microg/L. Urinary iodine concentration correlated with the iodine content of salt in all countries. Median values of thyroid volume were within the normal range for age in all countries, but the goiter prevalence varied markedly from 3.1% to 25.0% because of scatter. The median iodine content of salt from local markets (2734 samples) varied from 5.9 parts per million (ppm) to 78 ppm and was greater than 15 ppm in 83.1% of all samples. Only seven countries had higher than 15 ppm iodine in 80% of the samples, and only three had greater than 15 ppm in at least 90%. Iodized salt was available at retail level in all countries but its median iodine content was within the recommended range (20-40 ppm) in only five. This study, the first to apply a standardized assessment strategy to recent iodine nutrition in Latin America, documents a remarkable success in the elimination of iodine deficiency by iodized salt in all but 1 of the 13 countries. Some iodine excess occurs, but side effects have not been reported so far, and two countries have already decreased their legal levels of salt iodization and improved the quality control of iodized salt, in part because of our results. The present work should be followed by regular monitoring of iodine nutrition and thyroid function, especially in the countries presently exposed to iodine excess.

Latin American Thyroid Society recommendations for the management of thyroid nodules

Several guidelines on diagnosis and treatment of thyroid nodules and cancer have recently been published. However, recommended practices are not always appropriate to different settings or countries. The aim of this consensus was to develop Clinical Guidelines for evaluation and management of patients with thyroid nodules applicable to Latin American countries. The panel was composed by 13 members of the Latin American Thyroid Society involved with research and management of thyroid nodules and cancer from different medical centers in Latin America. The consensus was produced based on the expert opinion of the panel with use of principles of evidence-based medicine. Following a group meeting, a first draft based on the expert opinion of the panel was elaborated and later circulated among panel members for further revision. After revision, this document was submitted to all LATS members for commentaries and considerations and finally revised and refined by the authors. The final recommendations represent state of the art on management of thyroid nodules applied to all Latin American countries.

PREVALENCIA DE BOCIO ENDEMICO POR EL METODO ECOGRAFICO, DETERMINACION DE YODURIAS y YODO EN SAL EN ESCOLARES DEL PARAGUAY.

Paraguay, pais mediterraneo ubicado en el corazon de America del Sur, con una superficie de 406.542 Km2 y con una poblacion de 5,8 millones de habitantes importa toda la sal que consume de paises cercanos como la Argentina, Brasil y Chile. En el presente estudio observacional, de tipo descriptivo utiliza el metodo ecografico para determinar el tamano y las caracteristicas de la glandula tiroides, se examinaron 1034 escolares de ambos sexos de 13 distritos del pais y fue realizado durante 3 meses del ano 2000. Los lugares elegidos tenian antecedentes de bajo consumo de sal yodada con valores de yoduria por debajo de 50 µg/L, como tambien la medicion de la yoduria por el metodo de trinitrito , el tenor de yodo en sal y la relacion talla/peso de los escolares estudiados. El 82.9% del volumen tiroideo de los escolares resulto dentro de los limites normales. Se detecto un volumen tiroideo aumentado en el 17.1% de los ninos segun la edad y sexo y en 22% segun la superficie corporal. Nodulos tiroideos se observaron en 5 ninos y solo1 nino tenia antecedentes de haber tenido cirugia tiroidea. El 53% de los distritos presentaron medias urinarias de yodo por encima de 200 µg/dL con un promedio de 301.3 µg/dL. El 40% de los distritos presentaron yodurias optimas (entre 100 y 199 µg/dlL) con una media de 145 µg/dL. Solo el 7% presento una media urinaria de yodo bajo 100 µg/dL. El estudio demostro una mejoria en la yodacion de la sal de consumo humano al compararlo con los realizados en 1988 en el Paraguay,sin embargo,existen riesgos de producir en la poblacion tirotoxicosis y enfermedades tiroideas autoinmunes por el porcentaje de yodo en la sal en aumento, por lo que se recomienda un seguimiento y control con los ajustes necesarios de los niveles de yodacion.

Perinatal Pituitary-Thyroid Function at High Altitude

Acute exposure of adult men to a high altitude environment results in transitory thyroid hyperactivity (1) and increased TSH secretion (2). The effect of high altitude on pituitary-thyroid function during perinatal life has little been studied. Normal low cord blood T4 levels have been reported (3), and a hypoxemic condition of the fetus has been suggested by high cord blood hematocrits (4), hyperplasia of bone marrow erythroid cells (5), lower birth weight (6), and by a higher incidence of prematurity (6) and neonatal mortality (7).

Elimination of iodine deficiency disorders from the Americas: a public health triumph

Historically, iodine defi ciency disorders aff ected most countries of the Americas. But now, the American continent is celebrating the elimination of iodine defi ciency disorders, a remarkable achievement highlighted at the Micronutrient Forum Global Conference in Cancun, Mexico, on Oct 24–28, 2016. The challenge now is to sustain this achievement. Iodine defi ciency causes goitre, impairs reproductive health and lowers IQ; this spectrum of disorders is termed the iodine defi ciency disorders. Iodine defi ciency disorders were historically widespread in the Americas because of iodine-poor soils, particularly in mountainous areas. Reports during European colonisation described endemic goitre and cretinism in native Americans. In the early 20th century, iodine defi ciency disorders were recognised as a public health problem in most of the countries of the American continent. Endemic goitre was particularly severe in the mountain ranges extending from the Pacifi c northwest, through Mexico and Central America, and the Andes, to the southern tip of Chile. For example, in the goitre belt in the USA and Canada until the 1920s, which included the Pacifi c northwest, the midwest and the Appalachians, 26% to 70% of schoolage children had goiter. According to WHO, based on surveys in Latin America in the 1930s to 1960s, most countries had regions where the goitre prevalence was higher than 50% (fi gure, A). Recognising the severity of the problem, the Pan American Health Organization (PAHO) and WHO founded the Technical Group on Research in Endemic Goiter in 1961, headed by Prof John Stanbury from Harvard University. In a series of meetings between 1963 and 1983, the group defi ned the diagnosis and health consequences of iodine defi ciency disorders and made recommendations for prevention using iodised oil and iodised salt. Pioneering studies in the region identifi ed iodine defi ciency during pregnancy as a cause of irreversible foetal brain damage, and this led to a call for the elimination of iodine defi ciency disorders as an urgent global health priority at the World Summit for Children in 1990. This spurred a commitment by national governments throughout Latin America, working in partnership with UNICEF, PAHO and WHO, and the International Council for the Control of Iodine Defi ciency Disorders (ICCIDD, now the Iodine Global Network). The active presence of ICCIDD in the region since the 1980s has been instrumental in establishing multi-stakeholder coalitions responsible for the sustained success of national universal salt iodisation programmes. From the 1940s to the 1990s, most American countries passed legislation on iodised salt (table). Canada and Costa Rica were the fi rst to mandate iodisation of table salt in the 1940s, and the iodised salt programme in Canada continues to provide adequate iodine to the population: today the national median urinary iodine concentration, the WHO-recommended biomarker of iodine status of populations, is 174 μg/L, indicating adequate iodine intake. The Latin American ThyroMobil study in 2004 documented the remarkable success of iodised salt programmes using standardised urinary iodine concentration methods and thyroid ultrasound: iodine defi ciency disorders had been eliminated in all but one of the 13 countries surveyed in that year. Among the WHO regions, the Americas have had the highest proportion of households consuming well iodised salt for the past two decades. As a result, in 2016, the national median urinary iodine concentration