There is a paucity of studies regarding oxidative balance and selenium (Se) status in congenital hypothyroidism. Recently, more attention has been given to the use of Se supplementation as a new treatment for thyroid disorders. Oxidative stress increases in different thyroid disorders and causes many pathological outcomes. The present study aimed to determine the serum prooxidant-anti - oxidant balance (PAB), Se, thyroid stimulating hormone (TSH) and free thyroxine (FT4) concentration in congenital hypothyroidism patients and the association of their probable change with hematological indices.
Although there was no correlation between PAB and also Se with hematologic and biochemical markers in congenital hypothyroidism patients, changes in these two factors might be considered as a potential risk factor due to the other known effects of high PAB values and low Se concentrations (1).

Selenium plays a role in antioxidant status and, together with iodine, in thyroid function. Iodine deficiency exists in New Zealand during pregnancy and lactation, and selenium deficiency may further affect thyroid function. This study investigated selenium intakes of pregnant and lactating women, in Palmerston North, in the North Island of New Zealand. Dietary intake was estimated using three repeated 24-h dietary recalls. Dietary intake in pregnancy was also estimated from 24-h urinary excretion of selenium. Selenium concentrations were determined in urine and breastmilk using inductively-coupled plasma mass spectrometry. Median selenium intakes based on dietary data were 51 (39, 65) μg/day in pregnancy and 51 (36, 80) μg/day in lactation, with 61% and 68% below estimated average requirement (EAR). Median daily selenium intake in pregnancy based on urinary excretion was 49 (40, 60) µg/day, with 59% below EAR. Median selenium concentration in breastmilk was 11 (10, 13) µg/L and estimated median selenium intake for infants was 9 (8, 10) µg/day, with 91% below the Adequate Intake of 12 μg/day. These pregnant and breastfeeding women were at risk of dietary selenium inadequacy. Further research is required to assess selenium status in relation to thyroid function and health in this group (2).

Low selenium status is associated with increased risk of Graves' disease (GD). While several trials have discussed the efficacy of selenium supplementation for thyroid function, in GD patients, the effectiveness of selenium intake as adjuvant therapy remains unclear. In this systematic review and meta-analysis, we aimed to determine the efficacy of selenium supplementation on thyroid function in GD patients. Two reviewers searched PubMed, Web of Science, the Cochrane Central Register of Controlled Trials, and four Chinese databases for studies published up to October 31, 2017. RCTs comparing the effect of selenium supplementation on thyroid hyperfunction in GD patients on antithyroid medication to placebo were included. Serum free thyroxine (FT4), free triiodothyronine (FT3), thyrotrophic hormone receptor antibody (TRAb), and thyroid-stimulating hormone (TSH) levels were assessed. Ten trials involving 796 patients were included. Random-effects meta-analyses in weighted mean difference (WMD) were performed for 3, 6, and 9 months of supplementation and compared to placebo administration. Selenium supplementation significantly decreased FT4 (WMD=-0.86 [confidence interval (CI)-1.20 to -0.53]; p=0.756; I2=0.0%) and FT3 (WMD=-0.34 [CI-0.66 to -0.02]; p=0.719; I2=0.0%) levels at 3 months, compared to placebo administration; these findings were consistent at 6 but not 9 months. TSH levels were more elevated in the group of patients taking selenium than in the control group at 3 and 6, but not 9 months. TRAb levels decreased at 6 but not 9 months. At 6 months, patients on selenium supplementation were more likely than controls to show improved thyroid function; however, the effect disappeared at 9 months. Whether these effects correlate with clinically relevant measures remains to be demonstrated (3).

Graves' orbitopathy is a debilitating disorder which occurs in patients with autoimmune thyroid disease, mainly Graves' disease, and adds layers of complexity to management of both conditions. We conducted a comprehensive review of literature for publications relating to established and new management options for Graves' orbitopathy and have summarized key articles in this review. Initial evaluation of patients with Graves' disease should also include clinical evaluation for orbitopathy. If eye disease is present, patients are best managed by a multi-specialty team including an endocrinologist and ophthalmologist. All patients with Graves' orbitopathy benefit from risk factor modification and normalization of thyroid function tests. Patients with active, mild disease generally benefit from local therapies and selenium, while patients with moderate-to-severe disease usually require the addition of intravenous glucocorticoid therapy. If there is an inadequate response to glucocorticoid therapy, several second-line therapies have been investigated for use, including orbital radiotherapy (with additional glucocorticoids), rituximab, cyclosporine, mycophenolate mofetil, and methotrexate. Use of new biologic agents, mainly teprotumumab and tocilizumab, have demonstrated impressive reductions in disease activity and severity. If these results are confirmed, the treatment paradigm is likely to change in the future. Finally, there are several novel immunotherapies being investigated for Graves' disease, which may have treatment implications for Graves' orbitopathy as well. Overall, there are many encouraging advances in the therapy of Graves' orbitopathy that are making the future more promising for patients suffering from this disease (4).

References____________________________

(1) Alteration in Prooxidant-antioxidant Balance Associated with Selenium Concentration in Patients with Congenital Hypothyroidism.
Rostami S, Fathollahpour A, Abdi M, Naderi K.
J Med Biochem. 2018 Jul 1;37(3):355-363. doi: 10.1515/jomb-2017-0052. eCollection 2018 Jul.

(2) Selenium Intake in Iodine-Deficient Pregnant and Breastfeeding Women in New Zealand.
Jin Y, Coad J, Weber JL, Thomson JS, Brough L.
Nutrients. 2019 Jan 1;11(1). pii: E69. doi: 10.3390/nu11010069.

(3) Effects of Selenium Supplementation on Graves' Disease: A Systematic Review and Meta-Analysis.
Zheng H, Wei J, Wang L, Wang Q, Zhao J, Chen S, Wei F.
Evid Based Complement Alternat Med. 2018 Sep 26;2018:3763565. doi: 10.1155/2018/3763565. eCollection 2018. Review.

(4) Current and Emerging Treatment Strategies for Graves' Orbitopathy.
Genere N, Stan MN.
Drugs. 2019 Feb;79(2):109-124. doi: 10.1007/s40265-018-1045-9. Review.

Selenium is a trace element and a chemical element with the atomic symbol Se and atomic number 34. It has an atomic mass of 78.971 unified atomic mass units. and it is found in the human body (which requires only small amounts) inside the proteins and it produces selenoproteins important antioxidant and anti-inflammatory functions.

The name "selenium" comes from the Greek word "σελήν", which means "moon". It was discovered in 1817 by Jöns Jacob Berzelius, a Swedish chemist, who found the element while studying sulfuric acid from a factory in Sweden.

It's a nonmetal with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium.

Selenium is not synthesized in a laboratory or factory setting because it's a basic chemical element. Instead, it's extracted from the minerals in which it occurs naturally. 

The extraction process usually involves roasting the minerals in the presence of oxygen or air to convert selenium to selenium dioxide, which is then dissolved in water to produce selenous acid. This can then be reduced to selenium using sulfur dioxide.

What it is for and where

Selenium plays an important role, together with iodine, in thyroid function, for production of thyroid hormones and in brain development.

• Electronics. Selenium is used in the electronics industry to fabricate rectifiers, solar cells, and photocopiers. It's also used in surge protectors and light meters for cameras.
• Glass Manufacturing. Selenium is used in the glass industry to decolorize glass and to make red and yellow pigments. It can also be used to reduce the transmission of sunlight in architectural glass, giving it a bronze tint.
• Health and Nutrition. Selenium is an essential trace element in the human diet and is a component of several major metabolic pathways, including thyroid hormone metabolism and immune function. It's often included in dietary supplements.
• Photography. Selenium toners are used to improve the appearance of black and white prints and delay the onset of fading.
• Agriculture. Selenium is sometimes used to boost the selenium content of agricultural soils in regions where dietary selenium is low.
• Metallurgy. Selenium is used in the production of steel and lead to improve their machinability.
• Rubber Industry. Selenium is used as a vulcanizing agent in the production of rubber.
• Solar Energy. Selenium is used in thin-film solar cells in combination with copper, indium, and gallium to form the semiconductor material.

Safety

Please note that while selenium has many beneficial uses, it is toxic in large amounts, and care must be taken in its use and handling.

Chemical safety

Selenium studies

• Molecular Formula: Se
• Molecular Weight: 78.971g/mol
• CAS: 7782-49-2
• EC Number: 231-957-4
• MDL number: MFCD00134090
• PubChem Substance ID: 24852583

 Here are some of its properties:

Thermodynamic Properties:

• Phase at STP: Solid
• Melting point (gray selenium): 217 °C
• Boiling point (gray selenium): 684.9 °C

Electromagnetic Properties:

• Magnetic type: Diamagnetic
• Color: Gray
• Refractive index (gray selenium): 1.000895
• Reactivity:
• Valence: 6
• Electronegativity: 2.55
• Electron affinity: 2.021 eV
• First ionization energy: 9.753 eV

Material Properties:

• Mass density: 4.28 g/cm³ (black selenium), 4.39 g/cm³ (red selenium), 4.81 g/cm³ (gray selenium)
• Mohs hardness: 2 (≈ gypsum)
• Young modulus: 10 GPa
• Sound speed: 3350 m/s
• Thermal conductivity: 0.52 W/(m K)

Atomic Properties:

• Term symbol: ³P_2
• Atomic radius: 115 pm

Abundances:

• Universe abundance: 3×10^-6 mass% (rank: 32nd)
• Crust abundance: 5×10^-6 mass% (rank: 69th)
• Human abundance: 5×10^-6 mass% (rank: 33rd)

Nuclear Properties:

• Half-life: Stable
• Stable isotopes: Selenium-80 (49.61%)
• Unstable isotopes: Selenium-79 (0.295 Myr)