A history of the elimination of iodine deficiency disorders in the Americas: A dramatic achievement and lessons learned.

Iodine is essential for the synthesis of thyroid hormones, which regulate cell metabolism, growth, and development. While iodine deficiency (ID) causes adverse health effects across the lifespan, it is particularly problematic in pregnancy, when it can lead to irreversible fetal brain damage. A high prevalence of severe ID, manifesting as endemic goiter and cretinism, predated the arrival of European explorers in the Americas. Early 20th century surveys showed that most countries in the Western Hemisphere had regions with a goiter prevalence >50%. In North America, the introduction of iodized salt led to the elimination of ID by the 1950s. While most Latin American countries passed laws mandating salt iodization in the 1950s-1960s, initial programs met with limited success because laws were unenforced, monitoring was absent, and the importance of iodine nutrition was inadequately communicated. A renewed interest in ID prevention arose in the 1970s-1980s, when three Andean countries were the first in Latin America to implement effective salt iodization programs. Over the last three decades there has been a stronger political commitment to ID prevention across the region, alignment with the broader nutrition and development agenda, and a widespread recognition of optimal iodine nutrition as a fundamental human right. Currently, 92% of households in Latin America consume adequately iodized salt, and urinary iodine concentrations in schoolchildren reflect optimal iodine nutrition across the region. However, additional work remains. It is essential to ensure ongoing government commitment; to monitor population iodine status and the production, quality, and household consumption of iodized salt; and to maintain advocacy and communication strategies. Universal salt iodization programs must be harmonized with efforts to reduce salt intake for cardiovascular disease prevention. Ensuring optimal iodine nutrition in pregnant women, who may remain deficient even when intakes in schoolchildren are optimized, requires particular attention.

[From scientific research to health policy design: the experience of iodine deficiency elimination in Peru]. / De la investigación científica al diseño de políticas de salud: la experiencia con la eliminación de la deficiencia de yodo en Perú.

Scientific research is an essential public health function, enabling recognition of problems that compromise health and facilitating solutions. Research is essential to formulate health policy at a national level. There has been significant but inconsistent overall progress, due to economic conditions in low- and middle-income countries. An example that illustrates this situation is the investigation of iodine deficiency (ID) in Peru, and the application of the results for development of a public health program. The research demonstrated persistent ID, which causes fetal brain damage and subsequent mental retardation. The use of iodinated oil to prevent and treat ID was shown to have an immediate and long-term effect, and confirmed that urinary concentration of iodine was the best indicator of iodine intake. These results were accepted by the Ministry of Health, and the National Program for the Control of Endemic Goiter and Cretinism was created in 1983, achieving virtual elimination of ID by 1995.

La investigación científica es una función esencial en salud pública; permite reconocer problemas y situaciones que comprometen la salud y la identificación de soluciones. La investigación es esencial para formulación de políticas desalud. Es imperativo para los países tener sistemas nacionales de investigación. Últimamente, ha habido un significativo avance global, pero el crecimiento no es uniforme, las condiciones son escasas en países con ingresos medianos y bajos. Una experiencia que ilustra esta situación ha sido la investigación de la deficiencia de yodo (DI) en Perú y la aplicación de resultados para la creación de un programa de salud pública. La investigación demostró persistente DI, que durante la gestación causa daño cerebral y retardo mental, que el uso de aceite yodado en la prevención y tratamiento tiene efecto inmediato y larga duración, y validó la concentración urinaria del yodo como el mejor indicador de nutrición de yodo. Estos resultados fueron tomados en cuenta por el Ministerio de Salud y en 1983 se creó el Programa Nacional de Control del Bocio y Cretinismo Endémicos, que ha logrado la eliminación virtual de la DI desde 1995.

Eliminación y prevención de la deficiencia de yodo en mujeres gestantes de Perú / Elimination and prevention of iodine deficiency in pregnant women from Peru

RESUMEN La deficiencia de yodo (DI) causa daño a través de todos los ciclos de la vida, la vulnerabilidad es mayor durante la gestación y la infancia. La yodación universal de la sal (IUS) para consumo humano es la estrategia más costo-efectiva y sostenible para su control. Perú ha logrado la eliminación sostenida de los desórdenes por deficiencia de yodo (DDI) desde 1994. Objetivo: Determinar la efectividad del programa nacional de control de los DDI y la estrategia IUS para satisfacer el mayor requerimiento de yodo y asegurar la nutrición óptima de yodo de las mujeres embarazadas de la sierra, una región con severa deficiencia natural de yodo. Material y Métodos: El estudio ha incluido a 489 mujeres embarazadas de la sierra, seleccionadas entre las asistentes a control pre natal en los centros asistenciales. En cada sujeto se verificó el consumo de sal yodada y se colectó una muestra casual de orina para el análisis de la concentración de yodo y creatinina. Resultados: Según la encuesta de admisión el 99.6 % de los hogares consumen sal yodada. La mediana global de la concentración urinaria de yodo (CUI) 209 µg/L está dentro del rango adecuado para gestantes y demuestra un estado nutricional de yodo normal. La concentración de creatinina en la orina es normal. Conclusión: Estos resultados confirman la eficiencia y el éxito del programa nacional para la eliminación sostenida de los DDI, garantizando la nutrición normal de yodo durante la gestación y, por lo tanto, previniendo el riesgo de daño cerebral de los recién nacidos cada año en la sierra.

ABSTRACT Iodine is an essential element for synthesizing thyroid hormones, it is also essential for cell metabolism and tissue development, especially in the brain. Iodine requirements are higher during pregnancy and lactation. Iodine deficiency (ID) is a widespread condition all over the world; it is frequent in Peruvian highlands and rainforest. ID causes damage in all life periods, and vulnerability for this is greater during pregnancy and infancy. Universal salt iodination (USI) for human use is the most cost-effective and sustainable strategy for controlling ID. Peru has achieved the sustained elimination of iodine deficiency disorders (IDD) since 1994. Objective. To determine the effectiveness of the national program for controlling IDDs and the USI strategy for complying with the increased iodine requirement and to assure optimal iodine nutrition in pregnant women from the Peruvian highlands, a region with severe natural iodine deficiency. Material and Methods. The study included 489 pregnant women from the highlands, who were selected from those attending prenatal assessment in healthcare centers. Iodinated salty consumption was verified in each subject and a casual urine sample was collected for measuring iodine and creatinine concentration. Results. According to the admission survey, 99.6% of household use iodinated salt. The overall mean of iodine urine concentration (IUC) was 209 µg/L, which is well within the adequate range for pregnant women, and it shows a normal iodine nutrition status. The creatinine urinary concentration was normal. Conclusion. These results confirm the efficiency and success of the national program for the sustained elimination of IDDs, assuring normal iodine nutritional supply during pregnancy; and, therefore, preventing the risk for brain damage in newborns every year in the highlands.

Assessment of iodine status using dried blood spot thyroglobulin: development of reference material and establishment of an international reference range in iodine-sufficient children.

CONTEXT: Thyroglobulin (Tg) may be a valuable indicator of improving thyroid function in children after salt iodization. A recently developed Tg assay for use on dried whole blood spots (DBS) makes sampling practical, even in remote areas. OBJECTIVE: The study aim was to develop a reference standard for DBS-Tg, establish an international reference range for DBS-Tg in iodine-sufficient children, and test the standardized DBS-Tg assay in an intervention trial. DESIGN, PARTICIPANTS, AND INTERVENTIONS: Serum Tg reference material of the European Community Bureau of Reference (CRM-457) was adapted for DBS and its stability tested over 1 yr. DBS-Tg was determined in an international sample of 5- to 14-yr-old children (n = 700) who were euthyroid, anti-Tg antibody negative, and residing in areas of long-term iodine sufficiency. In a 10-month trial in iodine-deficient children, DBS-Tg and other indicators of iodine status were measured before and after introduction of iodized salt. RESULTS: Stability of the CRM-457 Tg reference standard on DBS over 1 yr of storage at -20 and -50 C was acceptable. In the international sample of children, the third and 97th percentiles of DBS-Tg were 4 and 40 microg/liter, respectively. In the intervention, before introduction of iodized salt, median DBS-Tg was 49 microg/liter, and more than two thirds of children had DBS-Tg values greater than 40 microg/liter. After 5 and 10 months of iodized salt use, median DBS-Tg decreased to 13 and 8 microg/liter, respectively, and only 7 and 3% of children, respectively, had values greater than 40 microg/liter. DBS-Tg correlated well at baseline and 5 months with urinary iodine and thyroid volume. CONCLUSIONS: The availability of reference material and an international reference range facilitates the use of DBS-Tg for monitoring of iodine nutrition in school-age children.

New reference values for thyroid volume by ultrasound in iodine-sufficient schoolchildren: a World Health Organization/Nutrition for Health and Development Iodine Deficiency Study Group Report.

BACKGROUND: Goiter prevalence in school-age children is an indicator of the severity of iodine deficiency disorders (IDDs) in a population. In areas of mild-to-moderate IDDs, measurement of thyroid volume (Tvol) by ultrasound is preferable to palpation for grading goiter, but interpretation requires reference criteria from iodine-sufficient children. OBJECTIVE: The study aim was to establish international reference values for Tvol by ultrasound in 6-12-y-old children that could be used to define goiter in the context of IDD monitoring. DESIGN: Tvol was measured by ultrasound in 6-12-y-old children living in areas of long-term iodine sufficiency in North and South America, central Europe, the eastern Mediterranean, Africa, and the western Pacific. Measurements were made by 2 experienced examiners using validated techniques. Data were log transformed, used to calculate percentiles on the basis of the Gaussian distribution, and then transformed back to the linear scale. Age- and body surface area (BSA)-specific 97th percentiles for Tvol were calculated for boys and girls. RESULTS: The sample included 3529 children evenly divided between boys and girls at each year ( +/- SD age: 9.3 +/- 1.9 y). The range of median urinary iodine concentrations for the 6 study sites was 118-288 micro g/L. There were significant differences in age- and BSA-adjusted mean Tvols between sites, which suggests that population-specific references in countries with long-standing iodine sufficiency may be more accurate than is a single international reference. However, overall differences in age- and BSA-adjusted Tvols between sites were modest relative to the population and measurement variability, which supports the use of a single, site-independent set of references. CONCLUSION: These new international reference values for Tvol by ultrasound can be used for goiter screening in the context of IDD monitoring.

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.

[Iodine content of cattle milk from mountain and coast from Perú]. / Contenido de yodo en leche de vacuno procedente de la Sierra y Costa del Perú.

With the objective to establish the cause-effect relationship between a geological area and the iodine content in cattle milk, and to estimate the contribution of milk consumption to the dietary iodine intake, the iodine content in cattle milk from the sierra and the coastal regions of Perú was determined. Milk samples were collected of cows from the three main productive zones of Perú, 62 in Cajamarca, 42 in Arequipa, both in the sierra, and 27 in Lima at the coast. The measurement of iodine was made by the method of Zak, based on the Sandell- Kolthoff reaction. The median values obtained were 24 microg/L in Cajamarca, 34 microg/L in Arequipa, and 170 microg/L in Lima. The median value in the sierra, 26 microg/L, was significantly lower than the one found in the coast. Moreover, while in the former 81% of individual values were below 50 microg/L, in the latter, on the contrary, 77% were above 80 microg/L. These results confirm that the iodine content in cattle milk is related to ecological factors. At the same time, they demonstrate that the iodine content in milk from the sierra is six times lower than in milk from the coast, and also that its consumption does not contribute significantly to satisfy the human physiological requirements of iodine in that zone.

De la investigación científica al diseño de políticas de salud: la experiencia con la eliminación de la deficiencia de yodo en Perú / From scientific research to health policy design: the experience of iodine deficiency elimination in Peru

RESUMEN La investigación científica es una función esencial en salud pública; permite reconocer problemas y situaciones que comprometen la salud y la identificación de soluciones. La investigación es esencial para formulación de políticas desalud. Es imperativo para los países tener sistemas nacionales de investigación. Últimamente, ha habido un significativo avance global, pero el crecimiento no es uniforme, las condiciones son escasas en países con ingresos medianos y bajos. Una experiencia que ilustra esta situación ha sido la investigación de la deficiencia de yodo (DI) en Perú y la aplicación de resultados para la creación de un programa de salud pública. La investigación demostró persistente DI, que durante la gestación causa daño cerebral y retardo mental, que el uso de aceite yodado en la prevención y tratamiento tiene efecto inmediato y larga duración, y validó la concentración urinaria del yodo como el mejor indicador de nutrición de yodo. Estos resultados fueron tomados en cuenta por el Ministerio de Salud y en 1983 se creó el Programa Nacional de Control del Bocio y Cretinismo Endémicos, que ha logrado la eliminación virtual de la DI desde 1995.

ABSTRACT Scientific research is an essential public health function, enabling recognition of problems that compromise health and facilitating solutions. Research is essential to formulate health policy at a national level. There has been significant but inconsistent overall progress, due to economic conditions in low- and middle-income countries. An example that illustrates this situation is the investigation of iodine deficiency (ID) in Peru, and the application of the results for development of a public health program. The research demonstrated persistent ID, which causes fetal brain damage and subsequent mental retardation. The use of iodinated oil to prevent and treat ID was shown to have an immediate and long-term effect, and confirmed that urinary concentration of iodine was the best indicator of iodine intake. These results were accepted by the Ministry of Health, and the National Program for the Control of Endemic Goiter and Cretinism was created in 1983, achieving virtual elimination of ID by 1995.

Diabetes gestacional, hipotiroidismo y concentración urinaria de yodo en embarazadas. Yodurias en escolares en Paraguay: Exceso de yodo en la sal y riesgo de hiper e hipotiroidismo / Gestational diabetes, hypothyroidism and iodine urinary concentration in pregnant women. Urinary iodine in schoolage children in Paraguay: Iodine excess in salt and hyper and hypothyroidism risk

The main inclicator of iodine nutritional status of salt for human con-sumption is the urinary concentration of iodine, which is useful in monitoring universal levels in salt. Paraguay has suffered deficiency in salt with highprevalence of goiter in thepopulation reaching48.6%. In 2000, results of the ThyroidMobileproject in Latin America showed a goiter prevalence of 17% but 79.6% of the consumed iodized salt was adequate in paraguayan households (more than 15 ppm of iodine). The average values of iodine urinary concentration in 4487 scholars was 437 µg/L, 30% of the average value was between the ideal of 100 to 199 µg/L and 46.1% were above 300 mg/L, with risk of excess iodine. Urinary concentration of iodine during pregnancy was measure for the first time in Paraguay in 200 women; the average was 484 µg/L but diabetes and hypothyroidism during pregnancy was observe in 50% of them. Objective: Determine iodine concentration in urine of the school population in 17 departments of the country and measure the levels of iodine in urine in 200 pregnant women from 15-37 years of age and their levels of glycaemia, and thyroid TSH. Methods: During the years, 2006 and 2007 were evaluated 4487 school randomized, in a probabilistic sample, 3198 in rural areas and 1,289 in urban areas; casual urine samples was collected to determine iodine content. The urinary concentration of iodine in two hundredpregnant women, concentration of iodine in salt, and levels of glycaemia and TSH were also included in the present study All candidates agreed with the informed consent under the ethics rules. Results: These data showed by comparing the levels of iodine in urine concentration in more than adequate and excessive level but this last was markedly elevated (93.8%). The median level greater than 300 µg/L was observed in 100% of the 4,487 urine samples, while the median urinary iodine levels of300-500 µg/L was 91.3% and above 500 was 9.7%. These levels showed the risk of developing thyroid autoimmune diseases. In 200 pregnancy women the average of urine concentration of iodine was 498 pcg/L, subclinical and clinical hypothyroidism and gestational diabetes was 50% of both. Conclu-sion: To obtain normal median urinary iodine levels is necessary to decrease the amount of iodine in salt. The main recommendation is to insist on adequate monitoring of iodized salt consumption. Also continue surveillance and monitoring in sentinel sites reporting the importance of adequate iodine intake of the population especially in pregnant women that also need to be warm about the diabetes during pregnancy but also a regimen is necessary to keep them within the normal levels of glycemia. The subclinical hypothyroidism has been also studied in the same patients.

El principal indicador del impacto de la yodación de la sal de consumo humano es la concentración urinaria de yodo la cual es útil en el monitoreo de la sal. En la encuesta del año 1988 realizada en el Paraguay, se alcanzó una prevalencia de bocio de 48,6% en la población escolar con un déficit de yodo en la sal, pero el año 2000 en el estudio del proyecto de Tiroides Móvil, se redujo por el método ecográfico a 17%. Ese mismo año la mediana de los niveles urinarios en niños escolares de 6-12 años fue 258 µg/L, considerando que 30% se encontraba entre el valor ideal de 100 a 199 µg/L y 46,1% sobre 300 µg/L, implicando un riesgo de exceso de yodo en dicha población con las posibles consecuencias de aparición tanto de hipo como de hipertiroidismo. El 93% presentó exceso de yodo en la sal y la mediana urinaria fue 437 ug/ mL. Un grupo de embarazadas han sido estudiadas en el Hospital San Pablo por primera vez en el Paraguay para la determinación de la yoduria, yodo en sal, diabetes gestacional, hipotiroidismo en el embarazo y sus valores antropométricos resultando un hipotiroidismo subclínico del 50% y diabetes gestacional del 50%. Objetivo: Determinar las yodurias en la población escolar de 6-12 años pre púber de ambos sexos en 17 departamentos del país y en una submuestra en embarazadas y también niveles de glicemia en el embarazo en un hospital de Asunción. Sujetos y Métodos: En el periodo del 2006-2007 fueron evaluados 4.487 escolares randomizados, en una muestra probabilística, 3.198 en el área rural y 1.289 en el área urbana con muestras en orina casual. El año 2015, doscientas embarazadas fueron estudiadas con muestras de glicemia en ayunas y 2 horas post prandial, dosaje de TSH, yodo en sal de 100 gramos de la sal de consumo en sus hogares y de orina para ver la concentración de yodo en sal y urinaria de yodo. Todos los candidatos fueron estudiados bajo consentimiento autorizado y de acuerdo a normas éticas. Resultados: Al comparar los niveles de yodo en orina en el nivel más que adecuado y el excesivo de la yoduria se vió que éste último nivel estaba marcadamente elevado (93.8%), que la mediana de los niveles mayores a 300 ug/L era del 100% del total de las 4.487 muestras de orina, mientras que la mediana de los niveles de yoduria entre 300-500 µg/L fue de 91,3% y por encima de 500 fue 9.7% lo cual implicó el riesgo de desarrollar enfermedades tiroideas autoinmunes. Las embarazadas presentaron una mediana urinaria de yodo 484 µg/L, diabetes gestacional e hipotiroidismo subclínico en 50%. Conclusión: Para normalizar los niveles de yoduria, es necesario disminuir la cantidad de yodo en la sal. La recomendación es insistir en el monitoreo de la adecuada yodación de las sales de consumo familiar y continuar con la vigilancia y el monitoreo constante en sitios centinelas divulgando la importancia de la adecuada ingesta de yodo a la población. Un régimen dietético a las embarazadas es necesario implementar en el primer trimestre del embarazo.

Prevalencia de bocio endemico por el metodo ecografico, determinación de yodurias y yodo en sal en escolares del Paraguay / Prevalence of endemic goiter with the ultrasonographic method, determination of orinary iodine and dosage of iodine content of salt in school of Paraguay

Paraguay, país mediterráneo ubicado en el corazón de America del Sur, con una superficie de 406.542 Km2 y con una población de 5,8 millones de habitantes importa toda la sal que consume de países cercanos como la Argentina, Brasil y Chile. En el presente estudio observacional, de tipo descriptivo utiliza el método ecográfico para determinar el tamaño y las características de la glándula tiroides, se examinaron 1034 escolares de ambos sexos de 13 distritos del país y fue realizado durante 3 meses del año 2000. Los lugares elegidos tenían antecedentes de bajo consumo de sal yodada con valores de yoduria por debajo de 50 æg/L, como también la medición de la yoduria por el método de trinitrito , el tenor de yodo en sal y la relación talla/peso de los escolares estudiados. El 82.9 por ciento del volumen tiroideo de los escolares resultó dentro de los limites normales. Se detectó un volumen tiroideo aumentado en el 17.1 por ciento de los niños según la edad y sexo y en 22 por ciento según la superficie corporal. Nódulos tiroideos se observaron en 5 niños y sólo1 niño tenía antecedentes de haber tenido cirugía tiroidea. El 53 por ciento de los distritos presentaron medias urinarias de yodo por encima de 200 æg/dL con un promedio de 301.3 æg/dL. El 40 por ciento de los distritos presentaron yodurias óptimas (entre 100 y 199 æg/dlL) con una media de 145 æg/dL. Solo el 7 por ciento presentó una media urinaria de yodo bajo 100 æg/dL. El estudio demostró una mejoría en la yodación de la sal de consumo humano al compararlo con los realizados en 1988 en el Paraguay,sin embargo,existen riesgos de producir en la población 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 yodación.