Lack of Association between Selenium Status and Disease Severity and Activity in Patients with Graves' Ophthalmopathy

Selenium supplementation in inactive moderate to severe Graves' orbitopathy patients: a randomized controlled trial

PURPOSE

This study was designed to evaluate the effect of selenium supplementation in inactive moderate-severe Graves' orbitopathy (GO) patients.

METHODS

This study was a single-center, placebo-controlled, double-masked, randomized trial. Inactive moderate-severe GO participants were randomized to receive six months of 200 micrograms/day of selenium supplementation or placebo. Thorough eye exams, clinical activity score (CAS), Graves' Ophthalmopathy quality of life questionnaire (GO-QOL), and serum selenium level were evaluated at baseline and 6 months after the interventions. The chi-squared or Fisher's exact test was used to compare categorical variables. The t-test and the paired t-test were used to compare continuous variables between two independent samples and two dependent samples, respectively.

RESULTS

A total of 25 participants were enrolled, 13 in the selenium group and 12 in the placebo group. Both groups had adequate baseline serum selenium levels at 98.96 ± 15.63 mcg/L and 102.55 ± 17.71 mcg/L, respectively. After 6 months of intervention, the selenium group showed a greater improvement in palpebral aperture (mean difference: -1.4 ± 1.7 mm, p = .04) compared to the placebo group (-0.3 ± 2.7 mm). Notably, 5(41.67%) people in the placebo group developed larger palpebral apertures. Proptosis, ocular motility, and soft tissue signs did not change significantly. GO-QOL and CAS score improvement showed no statistically significant difference between both groups. Minor adverse effects were observed.

CONCLUSIONS

Selenium supplementation has a positive effect on eyelid aperture even in inactive moderate-to-severe GO patients with a sufficient baseline selenium level.

Selenium supplementation in thyroid eye disease: an updated review from a clinical ophthalmic perspective

Thyroid eye disease (TED) consists of a spectrum of autoimmune orbital pathology that threatens patients' quality of life and vision. Research suggests that oxidative stress plays a role in both the thyroid gland and orbit. Selenium has been proposed as a potential therapeutic adjunct given its role in thyroid physiology and antioxidant metabolism. Furthermore, selenium status has been linked to multiple pathological thyroid states. Despite the preponderance of evidence demonstrating a role for selenium in thyroid disease, limited research exists highlighting its role in TED specifically. This review summarizes the pathophysiology and role of selenium in thyroid eye disease (TED) and the current body of evidence including in vitro and in vivo studies highlighting the role for supplementation in clinical ophthalmic practice. Notably, relatively lower selenium levels have been shown to have a modest correlation with severity of thyroid eye disease. Selenium supplementation has shown some benefit in patients with mild Graves' Orbitopathy in European populations presumed deficient. Despite the preponderance of evidence demonstrating a role for selenium in thyroid disease, limited data is available to conclusively expand its role in TED outside of a 6-month course of supplementation in selenium deficient or relatively deficient populations. Data subject to geographic and population differences in selenium levels limits the generalizability of supplementation in TED. Despite mechanistic evidence of its antioxidant effects in TED beyond the advantages of thyroid disease in general, the benefits of selenium supplementation should be interrogated further and contextually tailored in both clinical and research formats for ophthalmic practice.

Serum Selenium Levels in Patients With Graves Disease With or Without Thyroid Ophthalmopathy

BACKGROUND

Graves disease is one of the most common autoimmune thyroid diseases. Thyroid has the highest concentration of selenium (Se) in the body. Se plays a crucial role in the functioning of some thyroid enzymes; however, there are controversial results regarding the administration of serum Se levels in patients with Graves disease.

METHODS

In this study, patients with Graves disease with orbitopathy (GO group) or without orbitopathy (GD group) were recruited. Healthy individuals without a history of any disease were enrolled as the control group. Serum Se and thyroid hormone levels, including T3, T4, and thyroid-stimulating hormone (TSH), were measured using atomic absorption and radioimmunoassay techniques, respectively.

RESULTS

In this cross-sectional study, 60 and 56 patients and 58 healthy subjects were included in the GO, GD, and control groups. Serum Se levels in the GO, GD, and control groups were 94.53 ± 25.36 μg/dL, 96.82 ± 30.3 μg/dL, and 102.55 ± 16.53 μg/dL, respectively (P = .193). There was a reverse association between the serum Se level and thyroid hormones, including T3, T4, and TSH, in the GO group. However, serum Se levels exhibited a significant reverse association with T4 and TSH hormones but not with T3 in the GD group.

CONCLUSION

Our results showed no significant differences in the serum Se levels in the GO and GD groups compared with that in the control group. In addition, we did not detect any significant difference in the serum Se levels between the GO and GD groups.

Increased Incidence of Hashimoto Thyroiditis in Selenium Deficiency: A Prospective 6-Year Cohort Study

CONTEXT

In 2015, we reported an increased prevalence of thyroid disease in a county of low habitual selenium (Se) intake in comparison to a neighboring county with higher intake in a cross-sectional survey in Shaanxi Province, China.

OBJECTIVE

To explore longitudinal effects of low Se status, a prospective cohort study was conducted in the same area from 2013 to 2019, and thyroid peroxidase autoantibodies (TPO-Abs) and disease incidence were compared.

METHODS

A total 1254 individuals from 1500 reinvited participants were successfully enrolled. Venous blood, fingernails, and urine samples were collected and analyzed to evaluate thyroid status, TPO-Abs, serum Se, and urinary iodine. Diagnosis of Hashimoto thyroiditis (HT) was based on elevated thyrotropin, presence of TPO-Abs, and ultrasound characteristics. Se deficiency was categorized using a serum concentration of 80 µg/L as a threshold, and tested by logistic regression for a relationship to TPO-Abs and HT.

RESULTS

Se deficiency was observed in 46.2% of participants from the adequate-Se county (Ziyang) and in 89.7% from the low-Se county (Ningshan). Se concentrations in fingernails differed strongly by residency (Ziyang vs Ningshan; 678.7 vs 364.3 μg/kg; Z = -9.552; P < .001). Newly diagnosed HT in Ziyang was less frequent than in Ningshan (0.09% vs 0.31%; χ 2 = 4.350; P = .037). The conversion rate to seropositive TPO-Abs was 10.2% in Ningshan vs 5.6% in Ziyang. Excluding iodine as confounding factor, low-Se was confirmed as a risk factor for HT (relative risk [95% CI]; 3.65 [1.03-12.90]; P < .05).

CONCLUSION

The data indicate an increased incidence of TPO-Ab seroconversion with low Se supply and support the hypothesis that Se deficiency contributes to HT as a modifiable risk factor.

A Comprehensive Review on Selenium and Its Effects on Human Health and Distribution in Middle Eastern Countries

Selenium (Se) is an important microelement with numerous positive effects on human health and diseases. It is important to specify that the status and consumption of Se are for a specific community as the levels of Se are extremely unpredictable between different populations and regions. Our existing paper was based on the impacts of Se on human health and disease along with data on the Se levels in Middle Eastern countries. Overall, the findings of this comprehensive review show that the consumption and levels of Se are inadequate in Middle Eastern nations. Such findings, together with the growing awareness of the importance of Se to general health, require further work primarily on creating an acceptable range of blood Se concentration or other measures to determine optimal Se consumption and, consequently, to guarantee adequate Se supplementation in populations at high risk of low Se intake.

A Systematic Review on the Role of Antioxidants in Thyroid Eye Disease

Purpose

To systematically review the role of antioxidants in management of patients with thyroid eye disease (TED).

Methods

A literature search of the electronic databases was performed without restrictions on the date of publication till the end of March 2021, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Clinical trials, case-control studies, cohorts, case series, case reports, and experimental (including in vitro) studies in the English language were included. The primary outcome in human studies was improvement in severity, activity scores, and/or quality of life scores. There was a decrease in the level of H2O2-dependent oxidative stress, Hyaluronic acid release, reactive oxygen species, cell proliferation, or antifibrotic/antiproliferative actions in the in vitro studies.

Results

Out of 374 initially screened articles, 157 studies were selected, the full texts of 82 were reviewed, and 14 papers were finally included. There were 4 clinical and 10 in vitro studies from 1993 to 2018. While β-carotene, retinol, Vitamin E, Vitamin C, melatonin, resveratrol, N-acetyl-l-cysteine, and quercetin showed some efficacy in in vitro studies; allopurinol, nicotinamide, pentoxifylline, and selenium (Se) were effective in both clinical and experimental reports. Se was the only recommended antioxidant based on one high-level randomized controlled trial.

Conclusion

While different antioxidants could potentially be effective in the management of TED, no strong recommendation for any or combination of antioxidants could be made to be implemented in the daily practice.

Thyroid eye disease: From pathogenesis to targeted therapies

Thyroid eye disease (TED) is the most common extrathyroidal manifestation of autoimmune Graves’ hyperthyroidism. TED is a debilitating and potentially blinding disease with unclear pathogenesis. Autoreactive inflammatory reactions targeting orbital fibroblasts (OFs) lead to the expansion of orbital adipose tissues and extraocular muscle swelling within the fixed bony orbit. There are many recent advances in the understating of molecular pathogenesis of TED. The production of autoantibodies to cross-linked thyroid-stimulating hormone receptor and insulin-like growth factor-1 receptor (IGF-1R) activates OFs to produce significant cytokines and chemokines and hyaluronan production and to induce adipocyte differentiation. In moderately severe active TED patients, multicenter clinical trials showed that inhibition of IGF-1R with teprotumumab was unprecedentedly effective with minimal side effects. The emergence of novel biologics resulted in a paradigm shift in the treatment of TED. We here review the literature on advances of pathogenesis of TED and promising therapeutic targets and drugs.

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.

Serum selenium levels in patients with Graves' disease: associations with clinical activity and severity in a retrospective case-control study

Objectives

To compare serum selenium levels in Graves' patients and non-Graves' control participants and to evaluate associations between serum selenium levels and clinical features of Graves' orbitopathy (GO).

Methods

We conducted a single-centre, retrospective case-control study among 31 patients with diagnosed GO, 33 patients with Graves' disease without GO (GD), and 27 unaffected healthy participants enrolled between 2013 and 2020 at Severance Hospital. We compared serum selenium concentrations between the GD, GO, and healthy control groups, and analysed associations between serum selenium and GO patients' clinical activity scores (CAS), severity (assessed through modified NOSPECS scores), and other clinical features using multivariate linear regression analysis.

Results

Mean serum selenium levels were 109.30 ± 16.39 ng/mL, 111.39 ± 14.04 ng/mL, and 126.09 ± 21.09 ng/mL in GO patients, GD patients, and healthy control participants, respectively. Mean serum selenium levels in Graves' patients with and without orbitopathy were significantly lower than those in the healthy control group (p < 0.05), and mean selenium levels were slightly lower in GO than those in GD patients (p = 0.594). Serum selenium levels were significantly lower in GO patients with eyelid retraction than in patients without retraction (p = 0.038). However, serum selenium levels were not associated with CAS and modified NOSPECS scores (p = 0.241 and 0.801, respectively).

Conclusion

Serum selenium levels were significantly lower in Graves' patients with or without GO, compared to non-Graves' control participants. Selenium levels were not associated with CAS or NOSPECS scores, though we observed an association with eyelid retraction.

Anti-inflammatory and Antioxidant Effects of Selenium on Orbital Fibroblasts of Patients With Graves Ophthalmopathy

PURPOSE

In the present study, the authors investigated the effects of selenium on inflammation, hyaluronan production, and oxidative stress in primary cultured orbital fibroblasts of patients with Graves ophthalmopathy (GO).

METHODS

Orbital adipose/connective tissue specimens were obtained during the course of orbital surgery for patients with GO (n = 7) and other noninflammatory problems (n = 5). After incubation with various concentrations of sodium selenite for 48 hours, supernatants from primary cultures were collected. Hyaluronan and cytokine levels were measured using commercially available enzyme-linked immunosorbent assay kits. To determine the effect of selenium on reactive oxygen species (ROS) production stimulated by H2O2 (100 μM) for 30 minutes, the cells were pretreated with various concentrations of sodium selenite for 60 minutes.

RESULTS

Interleukin (IL)-6 and tumor necrosis factor-alpha levels were significantly higher in orbital fibroblasts of patients with GO than in orbital fibroblasts of control patients. Hyaluronan production was suppressed by selenium in cultured orbital fibroblasts of patients with GO. Inflammatory cytokines such as IL-1α, IL-8, and tumor necrosis factor-alpha were suppressed by selenium in cultured orbital fibroblasts of patients with GO. IL-1β and IL-6 were not suppressed by selenium in cultured orbital fibroblasts of patients with GO. Selenium pretreatment reduced intracellular ROS generation stimulated by H2O2 in cultured orbital fibroblasts of patients with GO.

CONCLUSIONS

In conclusion, hyaluronan production, inflammatory cytokines, and intracellular ROS generation were suppressed by selenium in cultured orbital fibroblasts of patients with GO. Several inflammatory cytokines may be suppressed by selenium in cultured orbital fibroblasts of patients with GO. This study provide the basis for use of selenium in the treatment of GO.

Relative selenium insufficiency is a risk factor for developing severe Graves' orbitopathy: a case-control study

Background/aims

Selenium (Se), an antioxidant agent, is effective in preventing mild Graves’ orbitopathy (GO) deterioration. However, the significant risk of low serum Se concentration for GO progression has not been identified. Here, we aimed to investigate the risk of relative Se insufficiency and to identify its optimal cut-off value in the development of disease severity in patients with GO.

Methods

Serum Se levels were prospectively measured in 100 consecutive patients with GO. The patients were classified into groups with mild and severe GO (logistic regression analysis outcome). A receiver operating characteristic (ROC) curve and the minimum p value corresponding to χ² statistics were analysed to select the optimal cut-off Se level for the diagnosis of severe orbitopathy.

Results

Thirty-two patients (32%) had mild GO and 68 (68%) had severe GO. The ROC revealed a cut-off Se level of 93 µg/L. Se levels ≤93 µg/L were observed in 48.5% and 12.5% of the patients in the severe and mild (p<0.001) groups, respectively. The risk estimate (OR) for an Se level ≤93 µg/L was 8.14 (95% CI 2.39 to 27.75). It remained a significant risk factor after adjusting for age, sex, thyroid status, smoking status, thyroidectomy and radioactive iodine.

Conclusion

Relative Se insufficiency (≤93 µg/L) is a potential risk factor for severe GO development. An evaluation of Se status is recommended in patients with GO for predicting disease progression and guiding supplementation therapy.

Selenium in thyroid disorders - essential knowledge for clinicians

In the 1990s, selenium was identified as a component of an enzyme that activates thyroid hormone; since this discovery, the relevance of selenium to thyroid health has been widely studied. Selenium, known primarily for the antioxidant properties of selenoenzymes, is obtained mainly from meat, seafood and grains. Intake levels vary across the world owing largely to differences in soil content and factors affecting its bioavailability to plants. Adverse health effects have been observed at both extremes of intake, with a narrow optimum range. Epidemiological studies have linked an increased risk of autoimmune thyroiditis, Graves disease and goitre to low selenium status. Trials of selenium supplementation in patients with chronic autoimmune thyroiditis have generally resulted in reduced thyroid autoantibody titre without apparent improvements in the clinical course of the disease. In Graves disease, selenium supplementation might lead to faster remission of hyperthyroidism and improved quality of life and eye involvement in patients with mild thyroid eye disease. Despite recommendations only extending to patients with Graves ophthalmopathy, selenium supplementation is widely used by clinicians for other thyroid phenotypes. Ongoing and future trials might help identify individuals who can benefit from selenium supplementation, based, for instance, on individual selenium status or genetic profile.

A pilot study on the beneficial effects of additional selenium supplementation to methimazole for treating patients with Graves’ disease

Background/aim

The aim of this study was to assess the effect of a combination use of methimazole (MMI) and selenium (Se) in the treatment of Graves’ disease (GD).

Materials and methods

A total of 103 newly diagnosed hyperthyroidism patients were randomized to MMI and MMI + Se combination groups. After treatment for 6 months, the levels of triiodothyronine (FT3), free thyroxine (FT4), thyrotropin receptor antibody (TRAb), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TGAb) were observed. An in vitro culture model of thyroid cells was established and the protein expression and mRNA levels of TRAb, TPOAb, and TGAb were determined by western blot and RT-PCR.

Results

A significant decrease in the levels of FT3, FT4, TRAb, TPOAb, and TGAb were observed in both groups along with a marked increase in TSH levels. Furthermore, the in vitro experiments showed that the protein expression and mRNA levels of TRAb, TPOAb, and TGAb decreased significantly. Also, compared to the MMI group, there was a greater improvement of these indices in the MMI + Se group.

Conclusion

We suggest that the combined use of MMI and Se could improve the thyroid activity in patients, which may provide an effective therapy for the treatment of GD in clinical settings.

Current and Emerging Treatment Strategies for Graves' Orbitopathy

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.

Insulin-like Growth Factor-I Receptor and Thyroid-Associated Ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is a complex disease process presumed to emerge from autoimmunity occurring in the thyroid gland, most frequently in Graves disease (GD). It is disfiguring and potentially blinding, culminating in orbital tissue remodeling and disruption of function of structures adjacent to the eye. There are currently no medical therapies proven capable of altering the clinical outcome of TAO in randomized, placebo-controlled multicenter trials. The orbital fibroblast represents the central target for immune reactivity. Recent identification of fibroblasts that putatively originate in the bone marrow as monocyte progenitors provides a plausible explanation for why antigens, the expressions of which were once considered restricted to the thyroid, are detected in the TAO orbit. These cells, known as fibrocytes, express relatively high levels of functional TSH receptor (TSHR) through which they can be activated by TSH and the GD-specific pathogenic antibodies that underpin thyroid overactivity. Fibrocytes also express insulin-like growth factor I receptor (IGF-IR) with which TSHR forms a physical and functional signaling complex. Notably, inhibition of IGF-IR activity results in the attenuation of signaling initiated at either receptor. Some studies suggest that IGF-IR-activating antibodies are generated in GD, whereas others refute this concept. These observations served as the rationale for implementing a recently completed therapeutic trial of teprotumumab, a monoclonal inhibitory antibody targeting IGF-IR in TAO. Results of that trial in active, moderate to severe disease revealed dramatic and rapid reductions in disease activity and severity. The targeting of IGF-IR with specific biologic agents may represent a paradigm shift in the therapy of TAO.

Role of Selenium Intake for Risk and Development of Hyperthyroidism

PURPOSE

To investigate the importance of dietary selenium (Se) for hyperthyroidism.

METHODS

We performed a more in-depth analysis of a large cross-sectional study of 6152 participants from two counties within the Shaanxi Province, China. These counties are characterized by different habitual Se intake. We investigated the effects of a different dietary Se supply (0.02, 0.18, 0.6, or 2.0 ppm Se) on disease development in a mouse model of Graves disease (GD).

RESULTS

The cross-sectional study revealed a comparable prevalence of hyperthyroidism, irrespective of Se intake, in both counties. However, an unexpected sex-specific difference was noted, and Se deficiency might constitute a risk factor for hyperthyroidism, especially in males. In a mouse model, pathological thyroid morphology was affected, and greater Se intake exerted some protecting effects on the pathological distortion. Circulating thyroid hormone levels, malondialdehyde concentrations, total antioxidant capacity, and the titer of GD-causing TSH receptor autoantibodies were not affected by Se. Expression analysis of the transcripts in the spleen indicated regulatory effects on genes implicated in the immune response, erythropoiesis, and oxygen status. However, the humoral immune response, including the CD4/CD8 or T-helper 1/T-helper 2 cell ratio and the concentration of regulatory T cells, was similar between the experimental groups, despite the difference in Se intake.

CONCLUSIONS

Our data have highlighted a sexual dimorphism for the interaction of Se and thyroid disease risk in humans, with indications of a local protective effects of Se on thyroid gland integrity, which appears not to be reflected in the circulating biomarkers tested.

A 2018 European Thyroid Association Survey on the Use of Selenium Supplementation in Graves' Hyperthyroidism and Graves' Orbitopathy

OBJECTIVE

Selenium (Se) supplementation has been suggested in the treatment of Graves' disease (GD). We sought to investigate Se prescription patterns for GD across European countries.

METHODS

Members of the European Thyroid Association were invited to participate in an online survey investigating the use of Se in GD either without or with orbitopathy (GO). Of 872 invited members, 244 (28%) completed the survey. After exclusion of basic scientists and non-European members, 197 responses were retrieved out of clinical trials (nearly half of clinician members), of whom 61 do not use Se. Thus, 136 respondents remained for further analyses.

RESULTS

Among the 136 analyzed respondents, most (64.7%) were not aware of the Se status in their populations, did not assess Se levels (78.7%), nor considered iodine status (74.3%). In GD without GO, 38.2% recommend Se supplementation ("sometimes" [27.2%], "frequently" [5.9%] or "always" [5.1%]). When GO occurs, 94.1% recommend Se supplementation ("sometimes" [39%], "frequently" [30.1%] or "always" [25%]). Of these, 60.1% recommend Se as an alternative to watchful waiting in patients with mild ocular involvement and 44.9% as an adjuvant to the established treatment modalities in patients with moderate to severe ocular involvement.

CONCLUSIONS

In Graves' hyperthyroidism without GO, 38.2% of ETA (European Thyroid Association) members recommend Se supplementation. Conversely, Se is recommended by the majority of respondents in GO, both in patients with mild and moderate to severe ocular involvement. This clinical practice is partially in disagreement with current European treatment guidelines that recommend Se as a 6-month treatment in mild GO only.

Selenium and Selenoproteins in Immune Mediated Thyroid Disorders

Selenium is an essential micronutrient that is required for the synthesis of selenocysteine-containing selenoproteins, processing a wide range of health effects. It is known that the thyroid is one of the tissues that contain more selenium. The “selenostasis” maintenance seems to contribute to the prevention of immune mediated thyroid disorders. Prospective, observational studies, randomized, controlled studies evaluating selenium supplementation, and review articles that are available in Medline and PubMed have undergone scrutiny. The differences concerning methodology and results variability have been analyzed. Several authors support the idea of a potential efficacy of selenium (mainly selenomethionine) supplementation in reducing antithyroperoxidase antibody levels and improve thyroid ultrasound features. In mild Graves’ orbitopathy, selenium supplementation has been associated with a decrease of the activity, as well as with quality of life improvement. Future research is necessary to clearly understand the selenium supplementation biologic effects while considering the basal selenium levels/biomarkers, selenoprotein gene polymorphisms that may be involved, underlying comorbidities and the major clinical outcomes.

Effects of Selenium Supplementation on Graves' Disease: A Systematic Review and Meta-Analysis

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.

Selenoproteins in human body: focus on thyroid pathophysiology

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.

Serum Trace Elements Profile in Graves' Disease Patients with or without Orbitopathy in Northeast China

Objective

The purpose of the present study was to investigate serum trace elements in Graves' disease (GD) patients with or without orbitopathy in Northeast China.

Methods

Patients with newly diagnosed Graves' disease (HyGD) (n = 66), GD patients with euthyroid status or subclinical thyroidism after treatment (EUGD) (n = 55), GO patients with euthyroid status or subclinical thyroidism after treatment (GO) (n = 57), and normal controls (NC) (n = 66) were enrolled in this study. Serum trace elements were measured with ICP-MS.

Results

Serum selenium (Se) levels in EUGD group (median: 7.53 µg/dL), HyGD group (median: 6.76 µg/dL), and GO group (median: 7.40 µg/dL) were significantly lower than those in NC group (median: 9.20 µg/dL, all P < 0.01). Serum copper (Cu) levels in GO group (median: 95.93 µg/dL) were significantly lower than those in the NC group (median: 113.59 µg/dL, P = 0.015). After being adjusted for multivariables, thyroid-specific antibodies grade was associated with low Se levels. Hyperthyroidism and thyroid-specific antibodies grade were associated with high Cu levels. In addition, orbitopathy was associated with low Cu levels.

Conclusions

Thyroid autoimmunity was associated with low Se levels. Hyperthyroidism and thyroid autoimmunity may be associated with relatively high serum Cu levels. Alternatively, ophthalmopathy may be related to low serum Cu levels.

Is selenium supplementation in autoimmune thyroid diseases justified?

PURPOSE OF REVIEW

This review provides an appraisal of recent evidence for or against selenium supplementation in patients with autoimmune thyroid diseases, and discusses possible effect mechanisms.

RECENT FINDINGS

Epidemiological data suggest an increased prevalence of autoimmune thyroid diseases under conditions of low dietary selenium intake. Two systematic reviews have evaluated controlled trials among patients with autoimmune thyroiditis and report that selenium supplementation decreases circulating thyroid autoantibodies. The immunomodulatory effects of selenium might involve reducing proinflammatory cytokine release. However, clinically relevant effects of selenium supplementation, including improvement in quality of life, are more elusive. In Graves' disease, some, but not all, trials indicate that adjuvant selenium supplementation enhances the restoration of biochemical euthyroidism, and might benefit patients with mild Graves' orbitopathy.

SUMMARY

The use of selenium supplementation as adjuvant therapy to standard thyroid medication may be widespread, but a growing body of evidence yields equivocal results. The available evidence from trials does not support routine selenium supplementation in the standard treatment of patients with autoimmune thyroiditis or Graves' disease. However, correction of moderate to severe selenium deficiency may offer benefits in preventing, as well as treating, these disorders. Molecular mechanisms have been proposed, but further studies are needed.

Update on thyroid-associated Ophthalmopathy with a special emphasis on the ocular surface

Thyroid-associated ophthalmopathy (TAO) is a condition associated with a wide spectrum of ocular changes, usually in the context of the autoimmune syndrome, Graves’ disease. In this topical review, we attempted to provide a roadmap of the recent advances in current understanding the pathogenesis of TAO, important aspects of its clinical presentation, its impact on the ocular surface, describe the tissue abnormalities frequently encountered, and describe how TAO is managed today. We also briefly review how increased understanding of the disease should culminate in improved therapies for patients with this vexing condition.

A 2016 Italian Survey about the Clinical Use of Selenium in Thyroid Disease

BACKGROUND

Selenium (Se) is a trace element that plays key roles in thyroid physiology. Se deficiency is associated with increased risk of thyroid disease. Some evidence suggests that Se supplementation may be beneficial in autoimmune thyroid disease (either hypo- or hyperthyroidism).

OBJECTIVES

We sought to examine the use of Se in daily clinical practice among Italian endocrinologists.

METHODS

Members of the Associazione Medici Endocrinologi (AME) were invited to participate in a web-based survey investigating the use of Se in different clinical conditions.

RESULTS

A total of 815 individuals (43.2% of AME members) participated in the survey, 778 of whom completed all of the sections. Among these respondents, 85.2% considered using Se for thyroid disease (58.1% rarely/occasionally and 27.1% often/always), and 79.4% prescribed Se for chronic autoimmune thyroiditis (AIT) (39.1% sometimes and 40.3% often/always). About two thirds of the respondents considered Se use in cases of subclinical autoimmune hypothyroidism, and about 40% had suggested Se use for patients with AIT who were planning pregnancy or already pregnant. About one fourth of the respondents had used Se for mild Graves' orbitopathy. Regarding the suggested daily dosage of Se, 60% of the respondents answered 100-200 µg, 20-30% recommended <100 µg, and 10-20% recommended >200 µg.

CONCLUSIONS

Se use is widely considered in daily clinical practice. Moreover, Se supplementation is often used or suggested for purposes extending beyond those supported by evidence-based medicine. Ongoing studies will better clarify how Se treatment can be properly utilized in thyroid disease management.