Antioxidant supplementation and serum lipids in patients with Graves' disease: effect on LDL-cholesterol

Lipid Profile Evolution in Graves' Disease Treated with Titration Regimen of Anti-Thyroid Drugs Versus Block and Replace Regimen

The aim was to compare the lipid profile of patients with GD treated with anti-thyroid drugs (ATDs) using a titration regimen versus a block and replace regimen. This is an 18-month prospective observational study. In this study were included 149 medically treated GD patients, aged+>+18 years. Pregnant women and patients treated with radioactive iodine therapy or partial/total thyroidectomy were excluded. Patients were divided into 2 subgroups: titration (A) and block and replace (B) therapy, according to the ATD regimen used. Thyroid and metabolic profile was measured at baseline and at least one visit during medical treatment. The whole group included 122 (81.87%) females (F) and 27 (18.12%) males (M), ratio F:M=4.5:1. As expected, at the time of diagnosis, thyrotoxic patients were with normal lipid profile. During medical treatment, in patients who achieved euthyroidism, the cholesterol levels increased as follows: in subgroup A: by 52.9 mg/dl (95% CI: 26.4-79.3), p<0.001 for total cholesterol (T-C), by 33.3 mg/dl (95% CI: 10.3-56.3), p=0.007 for low-density lipoprotein cholesterol (LDL-C) and by 11.44 mg/dl (95% CI: 3.08-19.79), p=0.009 for high-density lipoprotein cholesterol (HDL-C); in subgroup B T-C increased by 45.1 mg/dl (95% CI: 22.2-68), p<0.001 and for LDL-C by 33.57 mg/dl (95% CI: 12.72-54.42), p=0.003. No statistically significant increase in triglyceride levels was determined. Medical treatment of hyperthyroidism due to Graves' disease increased cholesterol levels regardless of the ATD regimen used.

Selenium and thyroid diseases

Selenium, a non-metallic element, is a micronutrient essential for the biosynthesis of selenoproteins containing selenocysteine. In adults, the thyroid contains the highest amount of selenium per gram of tissue. Most known selenoproteins, such as glutathione peroxidase, are expressed in the thyroid and are involved in thyroid hormone metabolism, redox state regulation, and maintenance of cellular homeostasis. Some clinical studies have shown that lack of selenium will increase the prevalence of several kinds of thyroid diseases. Selenium treatment in patients with Graves' orbitopathy has been shown to delay disease progression and improve the quality of life. Selenium supplementation in Hashimoto's thyroiditis was associated with the decreased levels of anti-thyroid peroxidase antibody and improved thyroid ultrasound structure. In thyroid cancer, various selenium supplements have shown variable anticancer activity. However, published results remain the conflicting and more clinical evidence is still needed to determine the clinical significance of selenium. This article reviews the strong association between selenium and thyroid disease and provides new ideas for the clinical management of selenium in thyroid disease.

Erythroid microRNA and oxidant status alterations in l-thyroxine-induced hyperthyroid rats: effects of selenium supplementation

BACKGROUND

Hypermetabolic state in hyperthyroidism causes oxidative stress. Erythrocytes are the cells that are involved in oxidant equilibrium in an organism and contain microRNA (miRNA). Selenium, which is an essential element for an organism, has antioxidant properties. The present study was aimed at investigating the effects of selenium supplementation in hyperthyroidism, on pro- and antioxidant enzymes, and miRNA (miR-144 and miR-451) expressions in the erythrocytes.

METHODS

Forty-eight Sprague-Dawley male rats were divided into 6 groups; control group, group fed with 0.5 mg/kg sodium selenite; group fed with 1 mg/kg sodium selenite; hyperthyroid group; hyperthyroid group fed with 0.5 mg/kg sodium selenite; and hyperthyroid group fed with 1 mg/kg sodium selenite. Malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), miR-144, and miR-451 expression levels were studied in erythrocyte hemolysates.

RESULTS

MDA levels were increased in the hyperthyroid group compared to the control group, and the group fed with 0.5 mg/kg sodium selenite (P<0.001 and P<0.01, respectively). GSH levels were increased in the hyperthyroid group and the hyperthyroid group fed with 0.5 mg/kg sodium selenite compared to the control group (P<0.001, and P<0.05, respectively). GSH levels of the hyperthyroid group fed with 1 mg/kg sodium selenite were decreased when compared with the hyperthyroid group (P<0.05). SOD levels of the hyperthyroid group were increased when compared with the control group (P<0.05, and P<0.001, respectively). Similarly, SOD levels of the hyperthyroid group fed with 1 mg/kg sodium selenite were lower than the hyperthyroid group (P<0.01). miR-144 values were increased in the hyperthyroid group and the hyperthyroid group fed with 0.5 mg/kg sodium selenite compared to the control group (P<0.001, and P<0.05 respectively). miR-451 expression was increased significantly in the hyperthyroid group compared to the control group (P<0.05).

CONCLUSIONS

Our findings showed that MDA, SOD and GSH levels increased, and miR-144 and miR-451 expressions changed in hyperthyroidism. Supplementation of 1 mg/kg sodium selenite was more effective than 0.5 mg/kg sodium selenite for normalizing the MDA, GSH, SOD, and miRNA levels in the hyperthyroid group.

Selenium in the Treatment of Graves' Hyperthyroidism and Eye Disease

Based on the role of oxidative stress in the pathogenesis of Graves' hyperthyroidism (GH) and Graves' Orbitopathy (GO), a therapy with the antioxidant agent selenium has been proposed and a number of studies have been performed, both in vitro and in vivo. In GH, reactive oxygen species (ROS) contribute to the thyroid and peripheral tissues damage. In GO, tissue hypoxia, as well as ROS, are involved in the typical changes that occur in fibroadipose orbital tissue and the perimysium of extraocular muscles. Antioxidants have been proposed to improve the effects of antithyroid drugs in GH patients, as well as the remodeling of orbital tissues in patients with GO. Here, we reviewed the literature on the possible beneficial effects and clinical use of selenium in the management of patients with GH and GO. A randomized clinical trial on the use of selenium in patients with mild GO provided evidence for a beneficial effect; no data are available on more severe forms of GO. Although the real effectiveness of selenium in patients with GH remains questionable, its use in the management of mild GO is generally believed to be beneficial, and selenium administration has been included in the clinical practice for the patients with mild eye disease.

Oxidative Stress in Graves Disease and Graves Orbitopathy

Oxidative stress is involved in the pathogenesis of Graves hyperthyroidism (GH) and Graves orbitopathy (GO) and an antioxidant approach has been proposed for both. In GH, a disbalance of the cell redox state is associated with thyroid hyperfunction and antithyroid medications may reduce oxidative stress. Tissue hypoxia participates in the pathogenesis of GO, and oxygen free radicals are involved in the typical changes of orbital tissues as reported by in vitro and clinical studies. Antioxidant agents, especially selenium, have been proposed as a therapeutic option for GH and GO. A clinical study regarding the use of selenium in mild GO has provided evidence for a beneficial effect in the short term, even though its beneficial effects in the long term are still to be investigated. In addition to selenium, a protective role of other antioxidant agents, i.e., quercetin, enalapril, vitamin C, N-acetyl-L-cysteine and melatonin has been suggested by in vitro studies, although clinical studies are lacking. Here, we review the role of oxidative stress and antioxidant agents in GH and GO.

Selenium in Graves Hyperthyroidism and Orbitopathy

PURPOSE

To review the in vitro and in vivo studies supporting a role of selenium for the treatment of mild Graves orbitopathy.

METHODS

Review of the current literature on the role of selenium in the management of Graves orbitopathy.

RESULTS

Graves orbitopathy (GO) is a disfiguring and disabling disorder usually observed in patients with Graves hyperthyroidism, and more rarely in patients with hypothyroid autoimmune thyroiditis or in the absence of overt thyroid dysfunction. Noninvasive treatments include intravenous glucocorticoids and orbital radiotherapy and are generally offered to patients with moderately severe GO. In contrast, patients with mild GO are generally treated only with local measures. Thus, the benefits of intravenous glucocorticoids in mild GO are limited and do not justify the risks that the treatment carries. However, a medical treatment for mild GO is heavily wanted, as a relevant proportion of patients have a significant decrease in their quality of life, and GO can progress into more severe forms. Because of the role of oxidative stress in the pathogenesis of GO, an antioxidant approach has been proposed and the antioxidant agent selenium has been shown to be effective for GO.

CONCLUSION

Studies have shown that a 6-month course of sodium selenite can improve the course of mild GO and prevent deterioration when compared with placebo.

Effects of selenium on short-term control of hyperthyroidism due to Graves' disease treated with methimazole: results of a randomized clinical trial

OBJECTIVE

In spite of previous conflicting results, an adjuvant role of selenium in the treatment of Graves' disease (GD) hyperthyroidism has been proposed. To address this issue, a randomized clinical trial was carried out aimed at investigating whether selenium is beneficial on the short-term control of GD hyperthyroidism treated with methimazole (MMI).

METHODS

Thirty newly diagnosed hyperthyroid GD patients were randomly assigned to treatment with: (i) MMI or (ii) MMI plus selenium. Primary outcomes were: control of hyperthyroidism and clinical and biochemical manifestations of hyperthyroidism [heart rate, cholesterol, sex hormone-binding globulin (SHBG), hyperthyroidism symptoms] at 90 days.

RESULTS

Baseline features of the two groups did not differ. Serum selenium at baseline was similar in the two groups and within the recommended range to define selenium sufficiency. Selenium increased with treatment in the MMI-selenium group and became significantly higher than in the MMI group. Serum malondialdehyde, a marker of oxidative stress, was similar in the two groups and decreased significantly with treatment, with no difference between groups. Administration of MMI was followed by a reduction of FT₃ and FT₄, with no difference between groups. Heart rate, SHBG and symptoms of hyperthyroidism decreased, whereas total cholesterol increased in both groups with no difference between groups.

CONCLUSIONS

Our study, carried out in a selenium-sufficient cohort of GD patients, failed to show an adjuvant role of selenium in the short-term control of hyperthyroidism. However, selenium might be beneficial in patients from selenium-deficient areas, as well as in the long-term outcome of antithyroid treatment.