Iodine, copper, zinc, selenium and molybdenum levels in children aged between 6 and 12 years in the rural area with iodine deficiency and in the city center without iodine deficiency in Hatay

Selenium in drinking water and cereal grains, and biomarkers of Se status in urine and fingernails of the Main Ethiopian Rift Valley population

BACKGROUND

Selenium (Se) plays an important role in human health, yet Se overexposure or deficiency can lead to deleterious health effects. This study aims to determine the concentration of Se in drinking water and staple cereal grain (maize, wheat, and teff) samples from the Main Ethiopian Rift (MER) Valley, and correspondingly, assesses Se biomarkers and their status as measured in the urine and fingernails of 230 individuals living in 25 MER communities.

METHOD

The concentration of Se in drinking water and cereal grain (maize, wheat, and teff) samples, and urine and fingernail samples were measured using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Demographic, anthropometric, and elemental concentrations were described by their quartiles and mean ± standard deviations. The 5th and 95th percentiles were used to describe the concentrations Se biomarkers ranges. The Se biomarker distributions in different study communities were further characterized according to Se levels found in drinking water, sex, and age using ANOVA, and multivariate regression. We conducted a correlation analysis (with Pearson correlation coefficient) and fitted a regression to evaluate the associations between these variables.

RESULTS

The mean concentration of Se in the drinking water samples was 0.66 (range: 0.015-2.64 µg/L; n = 25), and all samples were below the threshold value of 10 μg/L for Se in drinking water set by the World Health Organiation (WHO). In Ethiopia, most rural communities rely on locally produced cereal grains. We found mean Se concentrations (µg/kg) of 357 ± 190 (n = 14), 289 ± 123 (n = 14), and 145 ± 100 (n = 14) in wheat, teff, and maize, respectively. Furthermore, Se concentrations in drinking water showed no significant correlation with biomarker measures, indicating that the primary source of dietary Se is likely from local foods including staple grains. The mean±SD (5th-95th percentiles) of Se concentrations in fingernails and urine among study subjects were 1022 ± 320 (624-1551 µg/kg), and 38 ± 30 (1.9-100 µg/L), respectively.

CONCLUSION

A sizeable share of study participants (31%) fell below the lower limits of what is considered the currently accepted Se range of 20-90 µg/L in urine, though relatively few (only 4%) had similarly low fingernail levels. On the other hand, none of the samples reached Se toxicity levels, and the biomarker levels in this study are comparable to results from other studies that find adequate Se. Our results show that Se toxicity or deficiency is unlikely in the study population.

Trace elements and the thyroid

Trace elements, such as iodine and selenium (Se), are vital to human health and play an essential role in metabolism. They are also important to thyroid metabolism and function, and correlate with thyroid autoimmunity and tumors. Other minerals such as iron (Ir), lithium (Li), copper (Co), zinc (Zn), manganese (Mn), magnesium (Mg), cadmium (Cd), and molybdenum (Mo), may related to thyroid function and disease. Normal thyroid function depends on a variety of trace elements for thyroid hormone synthesis and metabolism. These trace elements interact with each other and are in a dynamic balance. However, this balance may be disturbed by the excess or deficiency of one or more elements, leading to abnormal thyroid function and the promotion of autoimmune thyroid diseases and thyroid tumors.The relationship between trace elements and thyroid disorders is still unclear, and further research is needed to clarify this issue and improve our understanding of how trace elements mediate thyroid function and metabolism. This paper systematically reviewed recently published literature on the relationship between various trace elements and thyroid function to provide a preliminary theoretical basis for future research.

Low urinary selenium levels are associated with iodine deficiency in Brazilian schoolchildren and adolescents

BACKGROUND

Selenium (Se) and iodine (Io) are important micronutrients for the proper functioning of the thyroid gland, as they are crucial for the synthesis and activation of the thyroid hormones (TH) triiodothyronine (T₃) and thyroxine (T₄).

OBJECTIVE

To evaluate the Se and Io nutritional status among schoolchildren.

METHODOLOGY

Cross-sectional, descriptive and analytical study conducted in 982 schoolchildren aged 6-14 years from public schools in the state of Bahia, Brazil. Sociodemographic and anthropometric variables, as well as urinary Se (USC) and Io concentrations (UIC) using the inductively coupled plasma mass spectrometry (ICP-MS) method and thyroid-stimulating hormone (TSH) from filter paper blood collection, were evaluated.

RESULTS

The median USC and UIC were 38.7 and 210.0 (IQR: 26.8-52.9 and 129.3-334.1 μg/L, respectively). The prevalence of iodine deficiency and excessive UIC were observed in 17.1% and 30.9% of schoolchildren, respectively. Concomitant low USC and IoD was found in 3.9% of schoolchildren. There was a positive correlation between USC and UIC (r = 0.60; p = 0.00). The median TSH was 0.95 (IQR: 0.69-1.30 µUI/L).

CONCLUSIONS

This study demonstrates that USC is a good biomarker for assessing Se status, meantime more studies are needed to establish cutoff USC in child population. Despite adequate median intake, a subgroup of schoolchildren had IoD and low USC. The correlation between UIC and USC point at the importance of two micronutrients, raising the question whether measuring Se should be included in monitoring programs that address the prevention of nutritional disturbances.

Selenium, Zinc, and Copper Status in Euthyroid Nodular Goiter: A Cross-Sectional Study

Background:

It is known that some elements are needed for normal thyroid gland functions. Iodine and selenium are the most well-known trace elements necessary for thyroid metabolism. Selenium is involved in the formation of thyroid hormones and the structure of the deiodinases associated with the development of the thyroid gland. While the role of zinc in thyroid metabolism is at the T3 receptor level, the role of copper is yet not clear.

Objective:

To compare the levels of serum trace elements such as selenium, zinc, and copper between the patients with euthyroid nodular goiter and healthy participants.

Methods:

This cross-sectional study included 98 patients with euthyroid multinodular goiter and 83 healthy subjects without thyroid disease. The demographics, thyroid hormone levels, and thyroid ultrasonography of the participants were recorded. Venous blood samples were centrifuged and sera samples were stored at -80°C until analysis of selenium, zinc, and copper levels. The levels of trace elements were determined by inductively coupled plasma-mass spectrometry (ICP-MS).

Results:

While serum, zinc, and selenium levels were significantly higher in the control group than the nodular goiter group, the copper levels were similar in the two groups. Trace elements were not correlated with thyroid hormone levels and thyroid volumes. Patients in the nodular goiter group were analyzed according to their solitary and multiple nodule status. The solitary and multiple nodular goiter groups were similar in terms of copper, zinc, and selenium levels.

Conclusions:

Deficiency of selenium and zinc may be associated with nodular goiter. Replacement of these trace elements may be useful for the prevention of nodular goiter, especially in deficient regions.

Global survey of urinary selenium in children: A systematic review

BACKGROUND

Selenium (Se) is an essential element in the human body that plays an important role in numerous fundamental physiological functions. However, the distribution of Se in the environment varies widely resulting in this element being available in a large concentration range in the ecosystem, and thus, in the human body. Urinary Se is a biomarker considered to be involved in adaptive mechanisms that help prevent health problems.

OBJECTIVES

The purpose of the present study was to conduct a systematic review to identify studies reporting the status of urinary Se in healthy children and create a global map.

METHODS

A literature search was conducted using MEDLINE (United States National Library of Medicine), Web of Science, Toxicology Bibliographic Information (TOXLINE), Latin-American and Caribbean Literature on Health Sciences (LILACS), and the grey literature. This study was registered in PROSPERO (international prospective register of systematic reviews) and was conducted in accordance with the PRISMA guidelines.

RESULTS

We identified 322 relevant articles, out of which 15 were included in this systematic review. The study identified a total of 4038 healthy children worldwide with urinary Se concentrations from 7.7 to 145.0 μg/L.

CONCLUSION

This is a pioneering study that provides evidence for the presence of Se in the urine of healthy children; we have shown that the available data is restricted to a small number of individuals and specific groups. Furthermore, there is a lack of information on urinary Se, especially in Latin America, Africa, and Asia.

Micronutrients, iodine status and concentrations of thyroid hormones: a systematic review

Context

The metabolism of thyroid hormones, which are essential for normal development, involves many proteins and enzymes. It requires iodine as a key component but is also influenced by several other micronutrients, including selenium, zinc, iron, and vitamin A.

Objective

This systematic review was designed to investigate the effect of micronutrient status and supplementation on iodine status and thyroid hormone concentrations.

Data Sources

Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines, electronic databases were searched from their inception to April 2016.

Study Selection

Human studies published in English and reporting data on micronutrient status and iodine status and/or thyroid hormone concentrations were included. Studies that examined the effect of micronutrient supplementation on iodine status and/or thyroid hormone concentrations were also included.

Data Extraction

A predesigned and piloted data extraction form was used to compile data from individual studies.

Results

A total of 57 studies were included: 20 intervention studies and 37 observational studies. Although observational evidence suggests that concentrations of selenium, zinc, and iron are positively associated with iodine status, data from randomized controlled trials fail to confirm this relationship.

Conclusions

Further studies are needed to provide greater understanding of the role of micronutrient status in iodine nutrition and thyroid function to ascertain the public health implications for populations worldwide.

Intake of Boron, Cadmium, and Molybdenum enhances rat thyroid cell transformation

Background

Epidemiologic data in volcanic areas suggest that environmental factors might be involved in the increase of thyroid cancer (TC) incidence. Recent reports indicate that several heavy metals and metalloids are increased in volcanic areas. This study aims to evaluate the combined effect of three of these elements Boron (B), Cadmium (Cd), and Molybdenum (Mo) - all increased in the volcanic area of Mt. Etna, in Italy - on thyroid tumorigenesis in the rat.

Methods

Female Wistar rats prone to develop thyroid tumors by low-iodine diet and methimazole treatment received ad libitum drinking water supplemented with B, Cd, and Mo at concentrations in the range found in the urine samples of residents of the volcanic area. At 5 and 10 months animals were euthanized, and their thyroid analysed. Statistical analysis was performed with a 2-way unpaired t-test.

Results

No toxic effect of the three elements on the growth of the animals was observed. A significant increase of histological features of transformation was observed in thyroid follicular cells of rats treated with B, Cd, and Mo compared with those of control group. These abnormalities were associated with decreased iodine content in the thyroid.

Conclusions

This study provides the evidence that slightly increased environmental concentrations of B, Cd, and Mo can accelerate the appearance of transformation marks in the thyroid gland of hypothyroid rats.

Changes in the Serum Levels of Trace Elements Before and After the Operation in Thyroid Cancer Patients

The present study aims to examine the changes in the serum levels of trace elements before and after the operation in thyroid cancer patients. The study registered 50 individuals, of whom 25 were female and 25 were male. The patients were allocated to four groups: group 1: male thyroid cancer patients group (n = 15), group 2: female thyroid cancer patients group (n = 15), group 3: male control group (n = 10), group 4: female control group (n = 10). The subjects in groups 1 and 2 were the patients who were post-operatively diagnosed with a pathological malignancy in the thyroid tissue samples. Blood samples were collected from all subjects before the operation, immediately after the operation, and on the post-operative day 15. Additionally, thyroid tissue samples were taken from all subjects post-operatively. Some elements in the blood and tissue samples were determined using the atomic emission method. Zinc and selenium levels of groups 1 and 2 in the pre- and post-operative measurements were significantly lower than those in the control groups (p < 0.05), but were higher in the thyroid tissue (p < 0.05). Serum zinc and selenium levels measured in the subjects on the post-operative day 15 were similar to those measured in the controls. Our study show that changes in the serum and thyroid tissue levels of trace elements like zinc and selenium, which play a critical role in thyroid function, might be associated with the pathogenesis of thyroid cancer.

Effects of Imbalance in Trace Element on Thyroid Gland from Moroccan Children

The major environmental factor that determines goiter prevalence is iodine status. However, other trace elements like selenium and zinc can influence the thyroid function. Hair samples (n = 68) were collected from goitrous and non-goitrous children aged 8-12 years living in the area of Al Haouz Marrakech-(Morocco). Trace element concentrations (Cr, Fe, Mg, Zn, Se, I) in hair were measured using flame atomic absorption spectroscopy, graphite furnace atomic absorption spectroscopy, and inductively coupled plasma mass spectrometry. Difference in the mean concentration of each trace element between groups was determined by ANOVA test. The mean concentration levels of I, Se, and Zn for goitrous children were lower and were similar to the mean concentrations reported in the literature for subjects with goiter. The regression results gave us a better model that revealed significant positive relations between thyroid volume and Zn contents and significant negative relation with I and Se. The overall findings of the present study revealed that the actual factors of thyroid gland volume increase are I and Se deficiency. This work could shed some light on the effects of trace elements-other than iodine-on the thyroid disorders.