Correlation of manganese with thyroid function in females having hypo- and hyperthyroid disorders

Prenatal metal concentrations and physical abnormalities in the Japan Environment and Children's Study

BACKGROUND

The association between prenatal metal exposure and congenital anomalies is unclear. We aimed to examine the association between exposure to cadmium, lead, mercury, selenium, and manganese and physical abnormalities.

METHODS

Data from 89,887 pregnant women with singleton pregnancies who participated in the Japan Environment and Children's Study (JECS) were used. The correlation between maternal blood metal concentrations and physical abnormalities during the second or third trimester was investigated using logistic regression models. Physical anomalies included those observed at birth or at 1 month, primarily from ICD-10 Chapter 17, particularly congenital anomalies associated with environmental factors (e.g., hypospadias, cryptorchidism, cleft lip and palate, digestive tract atresia, congenital heart disease, and chromosomal abnormalities) and minor abnormalities.

RESULTS

After adjusting for covariates, the OR (95% CIs) of physical abnormalities for a one-unit rise in Mn concentrations in all individuals were 1.26 (1.08, 1.48). The OR (95% CIs) of physical abnormalities in the 4th quartile (≥18.7 ng/g) were 1.06 (1.01, 1.13) (p-value for the trend = 0.034) compared with those in the 1st quartile (≤12.5 ng/g).

CONCLUSION

In Japan, maternal blood Mn concentrations above threshold during pregnancy may slightly increase the incidence of physical abnormalities.

IMPACT

Physical abnormalities (including minor anomalies and congenital anomalies) are associated with prenatal manganese concentrations. They are not associated with cadmium, lead, mercury, and selenium concentrations.

The association between the composite dietary antioxidant index and thyroid functionality among adults in the USA: NHANES 2007-2012

Objective

Composite Dietary Antioxidant Index (CDAI) values serve as a summary of an individual's combined dietary antioxidant intake. Although specific antioxidants are known to reduce thyroid damage from oxidative stress, the relationship between the CDAI and thyroid function remains uncertain. The purpose of this study was thus to investigate this relationship in greater detail while focusing on a representative American adult population.

Methods

A total of 6,860 subjects from the 2007-2012 NHANES cohort were included in this study. Associations between CDAI values and thyroid function were evaluated with weighted linear regression models and smoothed curve fitting. Subgroup analyses were also performed.

Results

The weighted mean (SD) values for variables analyzed in this study included a CDAI of 0.13 (0.06), serum free T4 (FT4) levels of 0.80 (0.01) ng/dL, and serum total T4 (TT4) levels of 7.80 (0.03) ug/dL. Lower CDAI values were found to be associated with higher levels of FT4 and TT4 using both unadjusted and adjusted models that accounted for relevant confounders (adjusted model, FT4 β = -0.003, p = 0.005; TT4 β = -0.035, p < 0.001). This negative correlation persisted when CDAI was categorized into quartiles (FT4, p for trend = 0.014; TT4, p for trend = 0.003).

Conclusion

These findings suggest that a diet rich in antioxidants, as reflected by higher CDAI scores, is associated with significant decreases in levels of free and total T4. Further analyses will be necessary to better clarify the underlying mechanisms behind these observations.

Manganese and thyroid function in the national health and nutrition examination survey, 2011-2012

CONTEXT

Manganese (Mn) exposure is prevalent, as it is found naturally as ionized trace elements and released into the environment as a byproduct of manufacturing and waste disposal. Animal and human studies have suggested variable effects on thyroid function, but the association of Mn exposure with thyroid function has not been evaluated in a national sample.

OBJECTIVE

To investigate the associations between serum and urinary Mn levels and serum thyroid hormone concentrations in a nationally representative sample.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTION

This was a cross-sectional analysis of data from the 2011-2012 National Health and Nutrition Examination Survey among 1360 participants.

MAIN OUTCOME MEASURES

Serum thyroid stimulating hormone (TSH), total triiodothyronine (T3), total thyroxine (T4), free T3, and free T4.

RESULTS

Serum Mn levels were positively associated with increasing total T4, free T3, and total T3 in the whole cohort (p < 0.01). Urinary Mn levels were not associated with thyroid hormone levels. When subgroup analyses were performed by gender, only males had total T4 associated with serum Mn [β = 0.01, p < 0.01, confidence interval (CI): 0.004-0.018]. In individuals under 22 years old, serum Mn was significantly associated with total T4 (β = 0.02, p = 0.002, CI: 0.008-0.029). Serum Mn was positively associated with Free T3 in both genders (β = 0.07, p < 0.001).

CONCLUSION

While our findings do not suggest clinical thyroid dysfunction, there is an association between serum Mn and subclinical changes in thyroid function that warrant further studies. Regulatory action should be considered as Mn-based organometallic compounds are being considered as replacements for lead in gasoline and may pose future risks to human health.

Manganese and Lead Exposure and Early Puberty Onset in Children Living near a Ferromanganese Alloy Plant

Manganese (Mn) and lead (Pb) have been associated with the deregulation of the neuroendocrine system, which could potentially favor the appearance of precocious puberty (PP) in environmentally exposed children. This study aims to evaluate the exposure to Mn and Pb and their potential effects in anticipating puberty in school-aged children living near a ferromanganese alloy plant in Bahia, Brazil. Toenail, occipital hair and blood samples were collected from 225 school-aged children. Tanner’s scale was used for pubertal staging. Mn in blood (MnB), toenail (MnTn) and hair (MnH) and blood lead (PbB) levels were measured by graphite furnace atomic absorption spectrometry. Puberty-related hormone concentrations were determined by chemiluminescence. The age at which girls’ breasts began to develop was inversely correlated with weight-for-age, height-for-age and BMI-for-age Z-scores (p < 0.05); pubarche also had similar results. Mn biomarker levels did not present differences among pubertal classification nor among children with potential PP or not. Furthermore, Mn exposure was not associated with the age of onset of sexual characteristics for either girls or boys. However, PbB levels were positively correlated with boys’ pubic hair stages (rho = 0.258; p = 0.009) and associated with the age of onset of girls’ pubarche (β = 0.299, 95%CI = 0.055−0.542; p = 0.017). Testosterone and LH concentrations were statistically higher in boys with an increased PbB (p = 0.09 and p = 0.02, respectively). Prospective studies are needed to better assess the association between exposure to Mn and Pb and the early onset of puberty.

Nutritional Management of Thyroiditis of Hashimoto

Since the thyroid gland is one of the organs most affected by autoimmune processes, many patients with thyroiditis of Hashimoto (TH) seek medical advice on lifestyle variance and dietary modifications to improve and maintain their hyroid function. In this review, we aim to present and discuss some challenges associated with the nutritional management of TH, focusing on environmental and dietary deficits, inflammatory and toxic nutrients, cyanotoxins, etc. We discuss the relationships among different diets, chronic inflammation, and microbiota, and their impact on the development and exacerbation of TH in detail. We share some novel insights into the role of vitamin D and melatonin for preserving thyroid function during chronic inflammation in autoimmune predisposed subjects. A comprehensive overview is provided on anti-inflammatory nutrients and ecological diets, including foods for cleansing and detoxification, which represent strategies to prevent relapses and achieve overall improvement of life quality. In conclusion, data from biomedical and clinical studies provide evidence that an appropriate dietary and lighting regimen could significantly improve the function of the thyroid gland and reduce the reactivity of autoantibodies in TH. Compliance with nutritional guidelines may help TH patients to reduce the need for medicines.

Exposure to common-use pesticides, manganese, lead, and thyroid function among pregnant women from the Infants' Environmental Health (ISA) study, Costa Rica

BACKGROUND

Pesticides and metals may disrupt thyroid function, which is key to fetal brain development.

OBJECTIVES

To evaluate if current-use pesticide exposures, lead and excess manganese alter free thyroxine (FT4), free triiodothyronine (FT3), and thyroid stimulating hormone (TSH) concentrations in pregnant women from the Infants' Environmental Health Study (ISA).

METHODS

At enrollment, we determined women's (n = 400) specific-gravity corrected urinary pesticide (μg/L) metabolite concentrations of mancozeb (ethylene thiourea (ETU)), pyrimethanil, thiabendazole, chlorpyrifos, synthetic pyrethroids, and 2,4-D. We also measured manganese hair (MnH) (μg/g) and blood (MnB) (μg/L), and blood lead (PbB) (μg/L) concentrations. To detect an immediate and late effect on thyroid homeostasis, we determined TSH, FT4 and FT3 in serum obtained at the same visit (n = 400), and about ten weeks afterwards (n = 245). We assessed associations between exposures and outcomes with linear regression and general additive models, Bayesian multivariate linear regression, and Bayesian kernel machine regression.

RESULTS

About 80%, 94%, and 100% of the women had TSH, FT4, and FT3 within clinical reference ranges, respectively. Women with higher urinary ETU, and pyrimethanil-metabolites, had lower FT4: β = -0.79 (95%CI = -1.51, -0.08) and β = -0.29 (95%CI = -0.62, -0.03), respectively, for each tenfold increase in exposure. MnB was positively associated with FT4 (β = 0.04 (95%CI = 0.00, 0.07 per 1 μg/L increase), and women with high urinary pyrethroid-metabolite concentrations had decreased TSH (non-linear effects). For the late-effect analysis, metabolites of pyrethroids and chlorpyrifos, as well as MnH, and PbB were associated decreased TSH, or increased FT4 and/or FT3.

DISCUSSION

Mancozeb (ETU) and pyrimethanil may inhibit FT4 secretion (hypothyroidism-like effect), while chlorpyrifos, pyrethroids, MnB, MnH, PbB and Mn showed hyperthyroidism-like effects. Some effects on thyroid homeostasis seemed to be immediate (mancozeb (ETU), pyrimethanil, MnB), others delayed (chlorpyrifos, MnH, PbB), or both (pyrethroids), possibly reflecting different mechanisms of action.

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.

Selected Essential and Toxic Chemical Elements in Hypothyroidism-A Literature Review (2001-2021)

Thyroid hormones are known for controlling metabolism of lipids, carbohydrates, proteins, minerals, and electrolytes and for regulating body temperature. Normal thyroid status depends on the chemical/elemental composition of body fluids and tissues, which changes depending on physiological state, lifestyle and environment. A deficiency or excess of certain essential chemical elements (selenium, zinc, copper, iron or fluorine) or exposure to toxic (cadmium or lead) or potentially toxic elements (manganese or chromium) interacts with thyroid hormone synthesis and may disturb thyroid homeostasis. In our review, accessible databases (Scopus, PubMed and Web of Science) were searched for articles from 2001-2021 on the influence of selected chemical elements on the development of hypothyroidism. Our review adopted some of the strengths of a systematic review. After non-eligible reports were rejected, 29 remaining articles were reviewed. The review found that disruption of the physiological levels of elements in the body adversely affects the functioning of cells and tissues, which can lead to the development of disease.

A case-control study on the association of mineral elements exposure and thyroid tumor and goiter

Thyroid tumor and thyroid goiter are prevalent disease around the world. In this case-control study, we investigated the association between exposure to a total of twelve mineral elements and thyroid disease as well as thyroid functions. Participants with thyroid tumor or goiter (N = 197) were matched with a healthy population (N = 197) by age (± 2 years old) and same sex. Questionnaires were used to collect data about the demographic characteristics and information of subjects. Serum and urine samples were collected simultaneously for each of the subjects. Mineral elements, iodine level of urine and levels of the total seven thyroid function indexes in serum were detected respectively. Conditional logistic regression was applied to estimate the associations between mineral elements and the risk of thyroid tumor and goiter through single-element models and multiple-element models. Multiple linear regression was used to evaluate relationships between mineral elements and percentage changes of thyroid functions. Higher concentrations of mineral elements in the recruited population were found in this study than other comparable studies, and the levels of chromium (Cr), manganese (Mn), nickel (Ni), arsenic (As), cadmium (Cd), selenium (Se), antimony (Sb), thallium (Tl) and lead (Pb) in the case group were lower than the control group. According to the single-element models, Cr, Mn, Ni, Sb and Tl showed significant negative associations with the risk of thyroid tumor and goiter, and, Cd showed nonmonotonic dose response. Cd and mercury (Hg) showed a nonmonotonic percentage change with T4, while Tl was associated with the increased FT4 in the control group. Therefore, Cd, Hg and Tl may disturb the balance of thyroid function to some extent, and Cr, Mn, Ni, Cd, Sb, and Tl may become potential influencing factors for the risk of thyroid tumor and goiter.

Manganese exposure and association with hormone imbalance in children living near a ferro-manganese alloy plant

It has been suggested that manganese (Mn) plays a fundamental role in the reproductive system through interference with the regulation of the secretion of hormones related to puberty. The objective of this study was to evaluate the environmental exposure to Mn and its effects on the endocrine regulation of hormones related to puberty in school-aged children living near a ferro-manganese alloy plant. Toenails, occipital hair, and blood samples were collected from 225 children, between 7 and 12 years of age, in four elementary schools in Simões Filho, Bahia, Brazil, who were exposed to different Mn levels owing to different Mn dust deposition rates. The Mn content was determined in the toenails (MnTn), hair (MnH), and blood (MnB), in addition to blood lead levels (PbB), by using graphite furnace atomic absorption spectrometry. Luteinizing hormone (LH), prolactin (PRL), estradiol (E₂), testosterone (T), and thyroid stimulating hormone (TSH) levels were determined by using a chemiluminescence method. Of the total participants, 50.2% were boys, with an average age of 9 years. PRL values were higher in children attending the school with a higher Mn deposition rate (p < 0.004). We observed that MnTn was positively correlated with PRL levels and exhibited a non-linear association with LH levels. None of the tested Mn biomarkers were associated with E₂, T, or TSH levels. To date, despite several animal studies that have focused on the correlation between Mn exposure and the endocrine regulation of hormones and pubertal development, very few studies have reported a similar relationship between environmental Mn effects and the human endocrine system. Our findings support the hypothesis that elevated exposure to Mn in children may be associated with hormonal imbalances that might trigger the early onset of puberty.

Exposure to environment chemicals and its possible role in endocrine disruption of children from a rural area

Endocrine disrupting chemicals (EDCs), including pesticides and metals, are present in rural areas, endangering the health of exposed populations. This work aimed to investigate the possible association between the exposure to these xenobiotics and thyroid dysfunction in children living in a rural community of Southern Brazil. Fifty-four children aged 5-16 years participated in this study. Peripheral biomarker evaluations were performed in periods of low and high exposure to pesticides. Thyroid ultrasonography was evaluated in the high exposure period. Blood levels of chromium (Cr), manganese (Mn), mercury (Hg), and lead (Pb), as well as hair Pb levels were positively correlated with thyroid stimulating hormone (TSH) concentrations and negatively associated with free thyroxine (fT4) levels in the low exposure period. Prolactin was positively associated with hair Mn in both periods. In the ultrasound tests, the majority of children presented a normal echogenicity of thyroid. Glucose was inversely associated with the biomarker of exposure to cholinesterase inhibitor insecticides, butyrylcholinesterase (BuChE). Lipid profile was above the recommended levels in both periods. In summary, our results show that children environmentally exposed to a mixture of xenobiotics in an agricultural community may have health impairments, especially on thyroid function, dyslipidemia, and glucose homeostasis disruption.

Statistical Evaluation of Trace Metals, TSH and T4 in Blood Serum of Thyroid Disease Patients in Comparison with Controls

The present study is based on the measurement of concentrations of selected trace metals (Fe, Zn, Cu, Co, Mn, Ni, Cr, Cd and Pb) and thyroid hormones (TSH and T₄) in blood serum of hypothyroid and hyperthyroid patients in comparison with healthy donors/controls in order to establish the imbalances of the trace metals in diseased subjects. The serum samples were digested in HNO₃-HClO₄ mixture and quantification of the metals was performed by flame atomic absorption spectrometry. Average levels of Fe, Ni, Cu, Cr, Pb and TSH were found to be significantly higher (p < 0.05) in the serum of hypothyroid patients compared with other donor categories, while mean concentrations of Mn, Cd and T₄ were significantly elevated in the serum of hyperthyroid patients compared with other donor groups (p < 0.05). The correlation pattern of trace metals in the serum of patient groups revealed significantly different mutual associations compared with the controls. PCA and CA pointed out the interferences of the toxic metals with essential metals in the serum of both patient groups compared with the controls. Most of the metals exhibited noticeable disparities in their concentrations based on gender, food habits and tobacco use for all donor groups. Thus, the pathogenesis of thyroid diseases is significantly affecting the essential trace and toxic metals balance in both patients groups.