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Huang HJ, Wang SS, Jin MM, Cheng BW, Liu Y, Liu XC, Yu QY, Yang XJ. Genetically predicted selenium concentrations and thyroid function: A two-sample Mendelian randomization study. Clin Endocrinol (Oxf) 2022; 98:813-822. [PMID: 36536522 DOI: 10.1111/cen.14867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022]
Abstract
OBJECTIVE The impact of selenium (Se) on human thyroid function remains unclear, with inconsistent results from recent epidemiological studies. Moreover, the observed associations are prone to bias due to potential confounding and reverse causation. Mendelian randomization (MR) analysis facilitates the large minimization of biases produced by environmental and lifestyle influences, providing unconfounded estimates of causal effects using instrumental variables. We aim to examine the association between Se concentrations and human thyroid function using a two-sample MR analysis. DESIGN AND METHODS Genetic instruments for Se concentrations, including toenail and blood (TAB) and blood Se concentrations, were identified from a genome-wide association study (GWAS) of blood Se (n = 5477) and toenail Se levels (n = 4162). GWAS summary statistics on thyroid phenotypes were downloaded from the ThyroidOmics consortium, including thyroid-stimulating hormone (TSH) (n = 54,288), free thyroxin (FT4) (n = 49,269), hypo (n = 53,423), and hyperthyroidism (n = 51,823). The MR study was conducted using the inverse-variance weighted (IVW) method, supplemented with the weighted median and the mode-based method. RESULTS Genetically determined TAB Se was negatively associated with FT4 (β = -.067; 95% confidence interval [CI] = -0.106, -0.028; p = 0.001) using the IVW analyses, as well in the additional analyses using the weighted median and weighted-mode methods. No evidence in heterogeneity, pleiotropy or outlier single-nucleotide polymorphisms was detected (all p > 0.05). Suggestive casual association between increased genetically determined TAB Se concentrations and decreased hypothyroidism risk was found by the IVW method (odds ratio [OR] = 0.847; 95% CI = 0.728, 0.985; p = 0.031). The causal effect of TAB Se on FT4 was observed in women (β = -.076; 95% CI = -0.129, -0.024; p = 0.004). However, the influence of genetically determined higher Se concentrations on TSH levels and hyperthyroidism revealed insignificance in the primary and sensitivity analyses. CONCLUSIONS The present MR study indicated that high Se concentration enable the decreasing of FT4 levels, and the effects of Se concentrations on FT4 remain sex-specific.
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Affiliation(s)
- Hui-Jun Huang
- Department of Epidemiology and Health Statistics, School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Shan-Shan Wang
- Department of Epidemiology and Health Statistics, School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Ming-Min Jin
- Department of Epidemiology and Health Statistics, School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Bin-Wei Cheng
- Department of Epidemiology and Health Statistics, School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yu Liu
- Department of Epidemiology and Health Statistics, School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xiao-Chen Liu
- Department of Epidemiology and Health Statistics, School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qiu-Yan Yu
- Department of Epidemiology and Health Statistics, School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xin-Jun Yang
- Department of Epidemiology and Health Statistics, School of Public Health and Management, Wenzhou Medical University, Wenzhou, Zhejiang, China
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Moravej H, Rakhshandehroo S, Ilkhanipoor H, Amirhakimi A, Rostami K, Yazdani N, Moghtaderi M, Mazlumi-abrazgah S. Role of Selenium Deficiency in Pediatrics with Acquired Hypothyroidism. Int J Prev Med 2021; 12:83. [PMID: 34584649 PMCID: PMC8428320 DOI: 10.4103/ijpvm.ijpvm_432_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 10/28/2020] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Although selenium is one of the nutrients that has an important role in the metabolism of thyroid hormones, it has been investigated in rare studies. This study aimed to evaluate role of selenium deficiency in children and adolescents with acquired hypothyroidism. METHODS This case and control study was conducted on 60 acquired hypothyroidism and 60 healthy children who had been referred to the pediatrics endocrine clinic in Shiraz, Iran, from November 2018 to April 2019. Some information such as age, gender, weight, height, duration of disease, and level of plasma selenium were recorded. Plasma selenium level was measured by atomic absorption spectrophotometer. Data were analyzed using SPSS software 21.0. RESULTS The mean of selenium level in the case and control groups were 93.77 ± 24.90 μg/dl and 85.96 ± 25.20 μg/dl, respectively. There was no significant difference between the two groups in the mean levels of selenium. Independent t-test showed no significant difference in the mean levels of selenium in male and female samples in the case group, but this difference was significant in the control group. CONCLUSION Selenium deficiency may not have significant role as a cause of acquired hypothyroidism in pediatric and adolescent age group, in south of Iran. Thus, it does not seem necessary to routinely check the level of selenium for patients with thyroid dysfunction.
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Affiliation(s)
- Hossein Moravej
- Neonatal Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Department of Pediatric Endocrinology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Shahrokh Rakhshandehroo
- Managing Director of Peyvand Pathobiology and Genetics Laboratory, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Homa Ilkhanipoor
- Department of Pediatric Endocrinology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Anis Amirhakimi
- Department of Pediatric Endocrinology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Khashayar Rostami
- Department of Pediatric, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Negar Yazdani
- Neonatal Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mozhgan Moghtaderi
- Neonatal Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
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Valea A, Georgescu CE. Selenoproteins in human body: focus on thyroid pathophysiology. Hormones (Athens) 2018; 17:183-196. [PMID: 29873029 DOI: 10.1007/s42000-018-0033-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 04/18/2018] [Indexed: 02/07/2023]
Abstract
Selenium (Se) has a multilevel, complex and dynamic effect on the human body as a major component of selenocysteine, incorporated into selenoproteins, which include the selenocysteine-containing enzymes iodothyronine deiodinases. At the thyroid level, these proteins play an essential role in antioxidant protection and hormone metabolism. This is a narrative review based on PubMed/Medline database research regarding thyroid physiology and conditions with Se and Se-protein interferences. In humans, Se-dependent enzyme functions are best expressed through optimal Se intake, although there is gap in our knowledge concerning the precise mechanisms underlying the interrelation. There is a good level of evidence linking low serum Se to autoimmune thyroid diseases and, to a lesser extent, differentiated thyroid cancer. However, when it comes to routine supplementation, the results are heterogeneous, except in the case of mild Graves' orbitopathy. Autoimmune hypothyroidism is associated with a state of higher oxidative stress, but not all studies found an improvement of thyroid function after Se was introduced as antioxidant support. Meanwhile, no routine supplementation is recommended. Low Se intake is correlated with an increased risk of developing antithyroid antibodies, its supplementation decreasing their titres; there is also a potential reduction in levothyroxine replacement dose required for hypothyroidism and/or the possibility that it prevents progression of subclinical hypothyroidism, although not all studies agree. In thyroid-associated orbitopathy, euthyroidism is more rapidly achieved if the micronutrient is added to traditional drugs, while controls appear to benefit from the microelement only if they are deficient; thus, a basal assay of Se appears advisable to better select patients who need substitution. Clearly, further Se status biomarkers are required. Future introduction of individual supplementation algorithms based on baseline micronutrient levels, underlying or at-risk clinical conditions, and perhaps selenoprotein gene polymorphisms is envisaged.
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Affiliation(s)
- Ana Valea
- Department of Endocrinology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania.
- Endocrinology Clinic, Clinical County Hospital, Cluj-Napoca, Romania.
- , Cluj-Napoca, Romania.
| | - Carmen Emanuela Georgescu
- Department of Endocrinology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
- Endocrinology Clinic, Clinical County Hospital, Cluj-Napoca, Romania
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Andrade GRG, Gorgulho B, Lotufo PA, Bensenor IM, Marchioni DM. Dietary Selenium Intake and Subclinical Hypothyroidism: A Cross-Sectional Analysis of the ELSA-Brasil Study. Nutrients 2018; 10:E693. [PMID: 29848946 PMCID: PMC6024881 DOI: 10.3390/nu10060693] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 05/21/2018] [Accepted: 05/28/2018] [Indexed: 12/31/2022] Open
Abstract
Selenium (Se) participates in several enzymatic reactions necessary for regulating the homeostasis of thyroid hormones. We aimed to analyze the association between dietary Se intake and subclinical hypothyroidism. Baseline data from the Longitudinal Study of Adult Health (Estudo Longitudinal de Saúde do Adulto-ELSA-Brasil) in Brazil were analyzed, with a final sample size of 14,283 employees of both sexes aged 35⁻74 years. Dietary data was collected using a previously validated food frequency questionnaire. Subclinical hypothyroidism was categorized as thyroid-stimulating hormone levels of >4.0 IU/mL and free prohormone thyroxine levels within normal limits, without administering drugs for thyroid disease. A multiple logistic regression model was used to assess the relationship between the presence of subclinical hypothyroidism and tertiles of Se consumption. The prevalence of subclinical hypothyroidism in the study sample was 5.4% (95% confidence interval [CI], 3.8⁻7.0%). Compared with the first tertile of Se intake, the second (odds ratio [OR], 0.79; 95% CI, 0.65⁻0.96%) and third (OR, 0.72; 95% CI, 0.58⁻0.90%) tertiles were inversely associated with subclinical hypothyroidism, however further research is needed to confirm the involvement of Se in subclinical hypothyroidism using more accurate methodologies of dietary assessment and nutritional status to evaluate this relationship.
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Affiliation(s)
- Gustavo R G Andrade
- Department of Nutrition, School of Public Health, University of São Paulo, São Paulo CEP 03178-200, Brazil.
| | - Bartira Gorgulho
- Department of Food and Nutrition, School of Nutrition, Federal University of Mato Grosso, Cuiabá CEP 78060-900, Brazil.
| | - Paulo A Lotufo
- Clinical and Epidemiological Research Center, University Hospital, University of São Paulo, São Paulo CEP 05508-000, Brazil.
| | - Isabela M Bensenor
- Clinical and Epidemiological Research Center, University Hospital, University of São Paulo, São Paulo CEP 05508-000, Brazil.
| | - Dirce M Marchioni
- Department of Nutrition, School of Public Health, University of São Paulo, São Paulo CEP 03178-200, Brazil.
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Rýdlová M, Růnová K, Száková J, Fučíková A, Hakenová A, Mlejnek P, Zídek V, Tremlová J, Mestek O, Kaňa A, Zídková J, Melčová M, Truhlářová K, Tlustoš P. The Response of Macro- and Micronutrient Nutrient Status and Biochemical Processes in Rats Fed on a Diet with Selenium-Enriched Defatted Rapeseed and/or Vitamin E Supplementation. BIOMED RESEARCH INTERNATIONAL 2017; 2017:6759810. [PMID: 28638832 PMCID: PMC5468552 DOI: 10.1155/2017/6759810] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/30/2017] [Accepted: 05/07/2017] [Indexed: 11/21/2022]
Abstract
The response of nutrient status and biochemical processes in (i) Wistar and (ii) spontaneously hypertensive (SHR) rats upon dietary intake of selenium- (Se-) enriched defatted rapeseed (DRS) and/or vitamin E fortification was examined to assess the health benefit of DRS in animal nutrition. Twenty-four individuals of each type of rat were used: The control group was fed with an untreated diet (Diet A). In Diets B and C, soybean meal was replaced with defatted DRS, which comprised 14% of the total diet. The selenized DRS application resulted in ~3-fold increase of Se content in the diet. Diet C was also fortified with the addition of vitamin E, increasing the natural content by 30%. The Se content of the blood and kidneys tended to increase in the DRS groups, where the changes were significant (P < 0.05) only in the case of SHR rats. The iodine (I) content and the proportion of iodide in rat livers indicated a lower transformation rate of iodide into organoiodine compounds compared to the control. Slight and ambiguous alterations in the antioxidative response of the rat were observed in the DRS groups, but the addition of vitamin E to the diet helped to moderate these effects.
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Affiliation(s)
- Michaela Rýdlová
- Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences in Prague, Prague, Czech Republic
| | - Karolína Růnová
- Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences in Prague, Prague, Czech Republic
| | - Jiřina Száková
- Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences in Prague, Prague, Czech Republic
| | - Alena Fučíková
- Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences in Prague, Prague, Czech Republic
| | - Anna Hakenová
- Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences in Prague, Prague, Czech Republic
| | - Petr Mlejnek
- Institute of Physiology, Academy of Science of the Czech Republic, Prague, Czech Republic
| | - Václav Zídek
- Institute of Physiology, Academy of Science of the Czech Republic, Prague, Czech Republic
| | - Jana Tremlová
- Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences in Prague, Prague, Czech Republic
| | - Oto Mestek
- Faculty of Chemical Engineering, University of Chemistry and Technology, Prague, Czech Republic
| | - Antonín Kaňa
- Faculty of Chemical Engineering, University of Chemistry and Technology, Prague, Czech Republic
| | - Jarmila Zídková
- Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Prague, Czech Republic
| | - Magdalena Melčová
- Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Prague, Czech Republic
| | - Klára Truhlářová
- Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Prague, Czech Republic
| | - Pavel Tlustoš
- Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences in Prague, Prague, Czech Republic
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Biological monitoring of exposure and effects in workers employed in a selenium-processing plant. Int Arch Occup Environ Health 2014; 88:623-30. [PMID: 25280955 DOI: 10.1007/s00420-014-0989-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 09/22/2014] [Indexed: 10/24/2022]
Abstract
PURPOSE The aim of the study was to assess external and internal selenium exposure and potential biological effects in employees working in a selenium-processing plant. METHODS Twenty male employees of a selenium-processing plant (exposed) and 20 age-matched male individuals without occupational selenium exposure (controls) participated in the study. Exposure to selenium at the workplace was determined by personal air sampling. Internal exposure was assessed by measuring total selenium concentration in plasma after a workshift and after holidays as well as by measuring the selenium concentration in urine before and after shift and after holidays. The activity of glutathione peroxidase (GPx) in blood and the prothrombin time were determined as biological effect parameters. RESULTS The exposure to selenium in the workplace air ranged from 8 to 950 µg/m(3) and exceeded in a large part current occupational exposure limits. The selenium levels in plasma samples of the exposed ranged from 49 to 182 µg/L during exposure and were significantly higher than the plasma levels observed after holidays as well as in the control group. The selenium concentration in pre- and post-shift urine samples did not differ significantly, and the average urinary selenium levels of the employees (18-1,104 µg/g creatinine) were significantly higher than those measured after holidays or determined in controls. Both the concentration of selenium in plasma and in urine did not correlate with the current external exposure of the employees at the workplace. However, we found a strong and significant association between the two biomonitoring parameters. In spite of the considerable high external exposure to elemental selenium, we did not find any effect on the GPx activity in blood as well as on the prothrombin time. CONCLUSIONS Both the selenium levels in plasma and urine may be used as biological monitoring parameters for the assessment of chronic occupational exposure to selenium. Nevertheless, the toxicokinetics of the urinary excretion of selenium remain still unclear and require further investigations. Moreover, our findings emphasise the necessity of a re-evaluation of occupational exposure limits for elemental selenium and inorganic selenium compounds.
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