The Prevention of Iodine Deficiency: A History.

Iodine is an essential component of the hormones produced by the thyroid gland and is, therefore, essential for mammalian life. A landmark trial in the early 20th century definitively demonstrated that iodine supplementation could prevent what was then known as "endemic goiter." Subsequent studies over the next decades demonstrated that iodine deficiency causes a spectrum of disease, including not just goiter, but also cretinism, intellectual impairment, and adverse obstetric outcomes. Salt iodization, first used in Switzerland and the United States in the1920s, has become the mainstay of iodine deficiency prevention efforts. The dramatic reduction in the global prevalence of iodine deficiency disorders (IDD) over the past 30 years represents an outstanding and under-recognized public health achievement. This narrative review provides an overview of critical scientific discoveries and advances in public health nutrition related to the prevention of IDD in the United States and worldwide. This review was written to commemorate the centennial of the founding of the American Thyroid Association.

[Regional target program «Prevention of iodine deficiency diseases for 202X-202X¼].

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Goiter in Brazilian modernism paintings / Bócio em pinturas da arte moderna brasileira

Objective: To evaluate Di Cavalcanti's artworks in which goiters are represented before and after the introduction of iodized salt to the Brazilian population. Methods: One hundred and thirty paintings by Di Cavalcanti from the 20's to 70's demonstrating necks were evaluated. All the paintings were observed in reproductions. The neck circumference in the paintings was measured. Since there were no standard thresholds of neck circumference, cutoffs were based on the median. Baseline characteristics of artworks were compared based on high and normal neck circumference categories using Student's t-test, Mann-Whitney-Wilcoxon test, or chi square test. Results: We analyzed 29 artworks which portray the neck of 60 women (84.5%), 8 men (11.3%) and 3 children (4.2%). The analyses of the neck circumference showed 23.3% of women (14/60), 12.5% of men (1/8), and 33.3% of children (1/3) with an abnormal profile of the neck circumference. The neck circumference ratio in 29 paintings showed that the relative sizes of the necks painted between the 1920's and 1950's (r=0.45; p=0.03), and painted between the 1960's and 70's (r= 0.54; p=0.003) have linearly decreased. The decades in which the artworks were painted explained 40.0% of the variation in size of the neck circumference (p=0.002). Conclusion: Art imitates life. Di Cavalcanti was not a physician, and probably did not have the intention to illustrate a pathological condition, although the images observed in this study should be considered as goiter or enlarged neck.

Objetivo: Avaliar as obras de Di Cavalcanti em que bócios estão representados, antes e após a introdução da iodação do sal para a população brasileira. Método: Foram avaliadas 130 pinturas de Di Cavalcanti entre os anos 1920 e 1970 demonstrando pescoços. Todas as pinturas foram observadas em reproduções. A circunferência do pescoço nas pinturas foi mensurada. Como não existia limite-padrão da circunferência do pescoço, os limites foram baseados na mediana. As características básicas das obras de arte foram comparadas por categorias da circunferência do pescoço em elevadas e normais, usando o teste t de Student, o teste de Mann-Whitney-Wilcoxon ou o teste qui-quadrado. Resultados: Analisamos 29 obras de arte que representavam o pescoço de 60 mulheres (84,5%), 8 homens (11,3%) e 3 crianças (4,2%). Ao analisar a circunferência do pescoço, 23,3% das mulheres (14/60), 12,5% dos homens (1/8) e 33,3% das crianças (1/3) demonstraram perfil anormal dela. A relação da circunferência do pescoço em 29 pinturas demonstrou que as circunferências do pescoço relativas aos pescoços pintados entre os anos 1920 e 1950 (r=0,45; p=0,03) e pintados entre os anos 1960 e 1970 (r=0,54; p=0,003) reduziram linearmente. As décadas em que as obra foram pintadas explicaram 40,0% da variação no tamanho da circunferência do pescoço (p=0,002). Conclusão: A arte imita a vida. Di Cavalcanti não era médico e, provavelmente, não tinha intenção de ilustrar uma condição patológica, embora as observações das imagens, neste estudo, tenham sido consideradas como bócio ou com aumento de volume do pescoço

Endemic Goiter and Iodine Prophylaxis in Calabria, a Region of Southern Italy: Past and Present.

Iodine, a micronutrient that plays a pivotal role in thyroid hormone synthesis, is essential for proper health at all life stages. Indeed, an insufficient iodine intake may determine a thyroid dysfunction also with goiter, or it may be associated to clinical features such as stunted growth and mental retardation, referred as iodine deficiency disorders (IDDs). Iodine deficiency still remains an important public health problem in many countries, including Italy. The effective strategy for the prevention and control of IDDs is universal salt iodization, which was implemented in Italy in 2005 as a nationwide program adopted after the approval of an Italian law. Despite an improvement in the iodine intake, many regions in Italy are still characterized by mild iodine deficiency. In this review, we provide an overview of the historical evolution of the iodine status in the Calabria region, located in the South of Italy, during the past three decades. In particular, we have retraced an itinerary from the first epidemiological surveys at the end of the 1980s to the establishment of the Regional Observatory of Endemic Goiter and Iodine Prophylaxis, which represents an efficient model for the surveillance of IDDs and monitoring the efficacy of iodine prophylaxis.

The effect of 17 years of increased salt iodization on the prevalence and nature of goiter in Croatian schoolchildren.

Background High goiter prevalence caused by iodine deficiency (medium content 5.6 mg potassium iodide [KI]/kg of salt, median urine iodine concentration [UIC] 68 µg/L) in Croatia was observed in 1991 and 1995 when salt was iodized with 10 mg KI/kg. A new regulation introduced in 1996, specified 25 mg KI/kg of salt resulting in an increase of median UIC to 248 µg/L. Afterwards, goiter prevalence was only assessed in two small studies. Methods In this study, we investigated the prevalence and etiology of goiter in 3594 schoolchildren 17 years after an increase in salt iodization in Croatia. Thyroid size was determined by palpation in 1777 girls and 1817 boys aged 10-18 years. In goitrous children, a thyroid ultrasound and thyroid-stimulating hormone, free thyroxine (fT4), free triiodothyronine (fT3), thyroid peroxidase (TPO) and thyroglobulin (TG) antibody measurements were performed. Results Goiter was found in 32 children (0.89% vs. 2.8% in 1991, p<0.00001 and 27% in 1995, p<0.00001), simple goiter (SG) in 18/32 (56%) goitrous children vs. 126/152 (82.8%) in 1991 p<0.00001, autoimmune thyroiditis (AT) in 13/32 (40.6%) vs. 19/152 (12.5%) in 1991 p<0.0009, nodules in four: two cysts, toxic adenoma and carcinoma (in 1991 two adenomas and one cyst), Graves' disease was not found (four in 1991). Subclinical hypothyroidism was found in three children. Thyroid disease was diagnosed in four of 32 children before the investigation. Increased iodine supply decreased goiter prevalence and SG/AT ratio in goitrous patients. Conclusions As thyroid abnormalities were found in 0.89% of children and some required treatment, thyroid examination is important in apparently healthy children regardless of sufficient iodization.

[Iodine prophylaxis, voices from the past after 65 years]. / Yodoprofilaxis, 65 años después suenan las voces del pasado.

In 1953, Dr. Felipe Rodríguez Moreno joined the Granada Research Group on Endemic Goiter, which was led by Dr. Ortiz de Landázuri. A high goiter prevalence (62% in women) was found out within the area, and that prevalence was observed to be related to the dietary habits of the time, being the most disadvantaged those who were showing a greater prevalence. A relationship between the high goiter prevalence and the family of the subjects with goiter was also found out, as they usually had a first-degree relative with affection. Iodine content of drinking water was poor throughout the area, so the prevalence was not significantly different between individuals who drank from different water sources. There were only two females with cretinism and two males affected by "idiocy", so the goiters were probably euthyroid. After introducing iodine prophylaxis with iodized salt in Güejar-Sierra, prevalence decreased from 53% to 13% between 1953 and 1958.

En el año 1953, el Dr. Felipe Rodríguez Moreno se incorpora para continuar el trabajo sobre endemia bociosa de la escuela de Granada, liderada por el Dr. Ortiz de Landázuri. En ese paisaje descubre una alta prevalencia de bocio (62% en mujeres), que se relacionaba con el tipo de dieta consumida, de tal forma que los más desfavorecidos tenían una prevalencia de bocio aún mayor. Así mismo, se encuentra una relación familiar en cuanto al bocio, de manera que los sujetos con bocio normalmente tienen un familiar en primer grado también afectado. El agua de bebida es pobre en yodo de forma generalizada, por lo que no hay diferencias significativas en la prevalencia de bocio según la fuente de la que se surtan los paisanos.  Solo se encontraron dos mujeres con cretinismo y dos varones afectados de "idiocia". Por ello, cabe pensar que se trata de bocios normofuncionantes.  Tras iniciar yodoprofilaxis con sal yodada en Güejar Sierra, se produce un descenso de la prevalencia de bocio de un 53% a un 13% entre los años 1953-1958.

[The iodine prophylaxis: the experience in the Autonomous Province of Bolzano (South Tyrol).] / La iodoprofilassi: l'esperienza della Provincia Autonoma di Bolzano (Alto Adige).

Since ancient times in South Tyrol there was evidence of endemic goitre caused by iodine deficiency. In the early 80's an epidemiological research on adults and primary and secondary school children reported in the least a prevalence of goitre from grade 1 B-3 (WHO) of 23,66% (limits WHO >5%) and an urinary iodine of 10,2 µgI/L. Therefore South Tyrol population presented heavy endemic goitre. In 1982 started a generalized iodine prophylaxis with alimentary iodined salt after an intense prevention campaign. In 1990 it has been done another epidemiological research on primary and secondary school children of the province (neck palpation, thyroid ultrasound, blood and urine tests) which revealed a prevalence of goitre from grade 1 B (WHO) of 1,6% (limits WHO >5%) and an urinary iodine of 137,1 µgI/L. Therefore in South Tyrol there was no more evidence of endemic goitre. In 2001 another research over primary and secondary school children, of the same areas and with the same approaches of the previous researches reported a prevalence of goitre of 1,5% and a median of urinary iodine of 230 µgI/L. On the basis of the data of Istituto Superiore di Sanità (National Institute of Health) can be stated that in the Province of Bolzano there's a low presence of congenital hypothyroidism. It has been observed an increase in the thyroiditis and in the diagnosis of thyroid cancer was marked an accentuation of papillar forms, less aggressive than the follicula. Unfortunately since 2001 no new epidemiological researches were done, due to lack of financial resources and the raising of other sanitary problems of higher priority.

Historical aspects of iodine deficiency control.

In 1895, iodine was characterized as an essential element of thyroid tissue by Baumann. The efficacy of iodine to prevent goiter was demonstrated by Marine in Northern USA in 1916-1920. Severe endemic goiter and cretinism had been almost entirely eliminated from continental Western Europe and Northern America before the 1930's; however large populations elsewhere and even some places in Western Europe (Sicily) were still affected up to the 2000's. Public health consequences of iodine deficiency are not limited to endemic goiter and cretinism. Iodine deficiency disorders include also increased neonatal death rate and decreased intellectual development, although these consequences are not included in the current estimation of the Global Burden Disease related to iodine deficiency. Severe iodine deficiency as a public health problem is now largely under control worldwide, but can still affect isolated places, in hard-to-reach and/or politically neglected populations. We emphasize the importance of maintaining international cooperation efforts, in order to monitor iodine status where iodine deficiency is now adequately controlled, and identify at-risk population where it is not. The goal should be now global eradication of severe iodine deficiency. Commercial distribution of iodized salt remains the most appropriate strategy. A randomized clinical trial in New Guinea clearly showed in the 1970's that correcting severe iodine deficiency early in pregnancy prevents endemic neurological cretinism. This supports the essential role of thyroid hormones of maternal origin on the normal fetal development, during the first trimester of pregnancy (i.e. when fetal thyroid is still not functional). A randomized clinical trial in Congo (RD) in the 1970's also showed that correcting severe iodine deficiency during pregnancy prevents myxœdematous cretinism, particularly prevalent in affected Congolese areas.

The way forward in Italy for iodine.

Italy is dealing with iodine deficiency since ancient times. In 1848 an ad hoc committee appointed by the king of Sardinia, identified extensive areas afflicted by endemic goiter and endemic cretinism in Piedmont, Liguria and Sardinia. Since then many epidemiological studies have been conducted in our country. These showed that iodine deficiency was present not only in mountain areas but also in coastal areas. In 1972 the iodization of salt at 15 mg/kg was allowed by law and iodized salt was distributed on request to selected endemic areas. Five years later the distribution was extended to the whole country. However the sale of iodized salt was not mandatory at that time and only a small fraction of the Italian population started using iodized salt. In 1991 the content of iodine in the salt was raised to 30 mg/kg and in 2005 a nationwide salt iodization program was finally implemented. Some years later a nationwide monitoring program of iodine prophylaxis was also implemented. Since 2005 the sale of iodized salt in Italian supermarkets has increased (34% in 2006, 55% in 2012), although it has been observed that the use of iodized salt is still low in the communal eating areas and in the food industry. These data are coherent with recent epidemiological studies showing that some regions in our country are still characterized by mild iodine deficiency and a high frequency of goiter and other iodine deficiency disorders. This implies that further efforts should be made to successfully correct iodine deficiency in Italy.

Iodine deficiency and nutrition in Scandinavia.

Iodine nutrition is a result of geological conditions, iodine fortification and monitoring strategies within a country together with the dietary habits of the population. This review summarizes the basis for the current iodine situation in the Scandinavian countries in order to identify gaps in knowledge, determine necessary future steps, highlight landmarks in Scandinavian iodine research and consider ongoing studies in Scandinavian countries with high international impact. Historically, iodine deficiency disorders such as goiter were common in Norway and Sweden, but not in Denmark. Different strategies have been used in Scandinavia to improve iodine nutrition. The major source of iodine is iodized salt in Sweden and from milk and dairy products in Norway. In Denmark, drinking water, milk, dairy products and iodized salt used in commercial production of bread are the important sources of iodine. The current iodine status in Scandinavia is not optimal and action is ongoing to increase iodination in Denmark, where there is mild iodine deficiency in the general population. Data from all three countries indicate insufficient iodine nutrition during pregnancy and there is a need for data from children, adolescents and young women. Monitoring a population's iodine status and dietary iodine sources is necessary to secure iodine nutrition in Scandinavia. Ongoing studies in Scandinavia will contribute significantly to the knowledge about the effects of mild to moderate iodine deficiency.

Iodisation of Salt in Slovenia: Increased Availability of Non-Iodised Salt in the Food Supply.

Salt iodisation is considered a key public health measure for assuring adequate iodine intake in iodine-deficient countries. In Slovenia, the iodisation of all salt was made mandatory in 1953. A considerable regulatory change came in 2003 with the mandatory iodisation of rock and evaporated salt only. In addition, joining the European Union's free single market in 2004 enabled the import of non-iodised salt. The objective of this study was to investigate the extent of salt iodising in the food supply. We examined both the availability and sale of (non-)iodised salt. Average sales-weighted iodine levels in salt were calculated using the results of a national monitoring of salt quality. Data on the availability and sales of salts were collected in major food retailers in 2014. Iodised salt represented 59.2% of the salt samples, and 95.9% of salt sales, with an average (sales-weighted) level of 24.2 mg KI/kg of salt. The average sales-weighted KI level in non-iodised salts was 3.5 mg KI/kg. We may conclude that the sales-weighted average iodine levels in iodised salt are in line with the regulatory requirements. However, the regulatory changes and the EU single market have considerably affected the availability of non-iodised salt. While sales of non-iodised salt are still low, non-iodised salt represented 33.7% of the salts in our sample. This indicates the existence of a niche market which could pose a risk of inadequate iodine intake in those who deliberately decide to consume non-iodised salt only. Policymakers need to provide efficient salt iodisation intervention to assure sufficient iodine supply in the future. The reported sales-weighting approach enables cost-efficient monitoring of the iodisation of salt in the food supply.

Effect of maternal iodine supplementation on thyroid function and birth outcome in goiter endemic areas.

OBJECTIVE: The study was undertaken to examine the clinical and endocrine parameters of thyroid in a total of 460 pregnant women belonging to non-goiter areas (group 1; n = 156) and endemic areas without (group 2; n = 154) and with iodine supplementation (group 3; n = 150), and their respective newborns. METHODS: Women of group 3 with visible goiter were administered two capsules of iodized oil orally each containing 200 mg of iodine, from weeks 6--8 of pregnancy. Blood samples were obtained from all groups during each trimester, at parturition (umbilical cord blood) and after delivery. Serum triiodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH) levels were measured by specific enzyme immunoassays. RESULTS: In group 2, serum T4 concentrations were low while T3 and TSH levels were high which showed hypothyroidism in the women of endemic areas. Goiter size decreased in most of the subjects who received a single dose of iodized oil and resulted in increase in serum concentrations of thyroid hormones; whereas, TSH levels decreased. Iodine supplementation also resulted in raised T4 and low TSH levels in the cord blood of neonates. During the course of study, two abortions, three still births and one cretin were reported in group 2; none was reported in group 3; and one still birth was reported in group 1. CONCLUSIONS: The oral administration of a single dose of iodized oil is capable of correcting iodine deficiency both clinically and endocrinologically in mothers and neonates. Iodine supplementation has the potential to positively impact the birth weight of newborns.

[Effectiveness of the program "School Milk" for the prevention of iodine deficiency].

Republic of Bashkortostan refers to iodine-deficient regions of Russia. The incidence of endemic multinodular goiter in 2012 in the Republic amounted to 33.2 per 100 thousand of the population. The purpose of the study is to evaluate the effectiveness of group iodine prophylaxis of schoolchildren through the use of iodized milk. The study included 181 children of primary school (pre-pubertal) age (8-10 years), it has been carried out in accordance with the recommendations of the WHO and the International Council for Control of iodine deficiency disorders using a unified system of identification of iodine deficiency states. Level of physical development was assessed according to anthropometric measurements, which were conducted by centile distribution tables according to age and sex, and the individual assessment of physical development was determined by the level of feature by its position in a number of centile. Assessment of iodine deficiency was carried out by determining levels of iodine excretion in a single urine sample. Iodine concentration in urine was determined by ceric ion-arsenious acid method. Frequency of iodine deficiency varying degrees before the iodine prophylaxis among urban children was 57.0%, among rural-92.3%. Urban junior schoolchildren showed severe iodine deficiency in 12.7% and moderate one in 16.4% of the cases, while in the countryside their prevalence was higher--27.4 and 35.2%, respectively. It was revealed that the number of children whose body growth values are within the average values is 36% in urban children, and 48.4% in rural areas. It should be noted that the low and very low body height predominate in rural students, it makes up 16.1% (while in the town it makes-up 2.3%). Iodine prophylaxis contributed to a significant reduction of iodine deficiency in children. In the town the median urinary iodine exceeded 100 mg/L and amounted to 159.4 mg/L. After iodine prophylaxis 82.5% of urban children and 72.1% of rural showed normal urinary iodine. When comparing the results of clinical and laboratory studies before and after the group prevention of iodine deficiency there has been revealed a positive trend in terms of reflecting the tensions of thyroid status.

An assessment of iodine nutritional status and thyroid hormone levels in children aged 8-10 years living in Zhejiang Province, China: a cross-sectional study.

UNLABELLED: Iodine is an essential nutrient for the synthesis of thyroid hormones that are critical for brain development. Iodine deficiencies were prevalent in China until the introduction of universal salt iodization (USI) in 1995. USI has been considered as the world's best achievements. This study aims to assess children's iodine nutrition and goiter status in Zhejiang Province in order to provide reasonable suggestions to the government for policy-making under the USI period. A cross-sectional survey in Zhejiang Province was conducted to children aged 8-10 years by stage cluster random sampling method. Spot urine samples were collected and analyzed. Thyroid ultrasonography examination was performed by special trained technicians using a 7.5-MHz transducer. Fasting venous blood samples were collected and analyzed for thyroid functional status. The median urinary iodine concentration was found to be 173.3 µg/L. The percentage of urine samples with iodine concentration <100 µg/L, 100-300 µg/L, and >300 µg/L was 15.5, 42.0, and 13.3 %, respectively. Goiter prevalence rate with iodine concentration <100 µg/L, 100-300 µg/L, and >300 µg/L was 6.8, 10.0, and 14.9 %, respectively, with no significant difference. Children with goiter have lower serum FT3 and T3 concentrations compared to those without goiter (p < 0.05). CONCLUSIONS: The median urinary iodine concentration of children aged 8-10 years falls in optimal iodine status as recommended by WHO/UNICEF/ICCIDD. Maintaining USI at an appropriate level is an important part of preventing iodine deficiency disorders and should always be based on routine monitoring urinary iodine concentration by the province.

La deficiencia de yodo en Cuba / Iodine deficiency in Cuba

Objetivo: caracterizar la magnitud y la severidad de la deficiencia de yodo en Cuba. Métodos: se caracterizó la magnitud y la severidad de la deficiencia de yodo en Cuba mediante la determinación de la yoduria y la prevalencia de bocio por inspección y palpación. Se realizó un estudio epidemiológico de corte transversal utilizando un muestreo complejo por conglomerados bietápico en tres estratos de selección: urbano, rural y montaña, el cual incluyó 67 municipios del país con un total de 2 101 escolares de 6 a 11 años. Resultados: se encontraron yodurias deficientes en el 6,4 por ciento de los niños evaluados a predominio del estrato de montaña. Se evidenció una ingesta excesiva de yodo en todos los estratos. La prevalencia de bocio fue de 27, 3 por ciento, considerada como endemia moderada con una mayor cifra en la montaña y sexo femenino. Los hallazgos indicaron el impacto de la yodación de la sal evaluado a través de la excreción urinaria como indicador de ingesta reciente. Conclusiones: el bocio endémico continúa siendo un problema nutricional poblacional, lo que sugiere realizar estudios de mayor profundidad para identificar las posibles relaciones causales(AU)

Objective: characterize the magnitude and severity of iodine deficiency in Cuba. Methods: characterization of the magnitude and severity of iodine deficiency in Cuba was based on determination of iodinuria and the prevalence of goitre by inspection and palpation. A cross-sectional epidemiological study was conducted using complex two-staged cluster sampling of three selected strata: urban, rural and mountainous, including 67 municipalities and a total of 2 101 school children aged 6-11. Results: deficient iodinuria was found in 6.4 percent of the children evaluated, with a predominance of the mountainous stratum. Excessive iodine intake was present in all strata. Goitre was classed as moderately endemic, with a prevalence of 27.3 percent and a predominance in the mountainous stratum and the female sex. Findings revealed the impact of salt iodization, which was evaluated through examination of urinary excretion as an indicator of recent salt intake. Conclusions: endemic goitre continues to be a nutritional problem in the population, pointing to the need to conduct more profound studies to identify possible causal relationships(AU)

La deficiencia de yodo en Cuba / Iodine deficiency in Cuba

Objetivo: caracterizar la magnitud y la severidad de la deficiencia de yodo en Cuba. Métodos: se caracterizó la magnitud y la severidad de la deficiencia de yodo en Cuba mediante la determinación de la yoduria y la prevalencia de bocio por inspección y palpación. Se realizó un estudio epidemiológico de corte transversal utilizando un muestreo complejo por conglomerados bietápico en tres estratos de selección: urbano, rural y montaña, el cual incluyó 67 municipios del país con un total de 2 101 escolares de 6 a 11 años. Resultados: se encontraron yodurias deficientes en el 6,4 por ciento de los niños evaluados a predominio del estrato de montaña. Se evidenció una ingesta excesiva de yodo en todos los estratos. La prevalencia de bocio fue de 27, 3 por ciento, considerada como endemia moderada con una mayor cifra en la montaña y sexo femenino. Los hallazgos indicaron el impacto de la yodación de la sal evaluado a través de la excreción urinaria como indicador de ingesta reciente. Conclusiones: el bocio endémico continúa siendo un problema nutricional poblacional, lo que sugiere realizar estudios de mayor profundidad para identificar las posibles relaciones causales

Objective: characterize the magnitude and severity of iodine deficiency in Cuba. Methods: characterization of the magnitude and severity of iodine deficiency in Cuba was based on determination of iodinuria and the prevalence of goitre by inspection and palpation. A cross-sectional epidemiological study was conducted using complex two-staged cluster sampling of three selected strata: urban, rural and mountainous, including 67 municipalities and a total of 2 101 school children aged 6-11. Results: deficient iodinuria was found in 6.4 percent of the children evaluated, with a predominance of the mountainous stratum. Excessive iodine intake was present in all strata. Goitre was classed as moderately endemic, with a prevalence of 27.3 percent and a predominance in the mountainous stratum and the female sex. Findings revealed the impact of salt iodization, which was evaluated through examination of urinary excretion as an indicator of recent salt intake. Conclusions: endemic goitre continues to be a nutritional problem in the population, pointing to the need to conduct more profound studies to identify possible causal relationships