Table 1.

Selenium in Graves’ Hyperthyroidism (GH).

Reference	Journal and years	Type of study	Methods	Dosage of compounds used	Results
Vrca VB. et al. (53)	Acta Pharm. 2012	Prospective, placebo-controlled, clinical trial	Fifty-five patients with newly diagnosed GH were randomized to receive methimazole alone or methimazole plus a fixed combination of antioxidant agents	The mixture of antioxidants contained: β-carotene (6 mg), selenium (60 μg), vitamins C (200 mg) and E (36 mg)	Beneficial effect on GH Better and faster normalization of thyroid function was observed in patients with GH treated with methimazole plus the mixture of antioxidant agents compared with control group. In addition, a better response to treatment, in terms of improvement of LDL-cholesterol levels, was found in patients treated with the antioxidant mixture compared with those given methimazole alone
Calissendorff J. et al. (2)	Eur Thyroid J 2015	Prospective, placebo-controlled, clinical trial	Thirty-eight consecutive patients with newly diagnosed and untreated GH were randomized to receive “block and replace” treatment with methimazole and levothyroxine, plus Selenium or alone for 9 months	Selenium (200 μg daily orally)	Beneficial effect on GH Patients treated with selenium had a better control of hyperthyroidism: at 18 weeks, the serum levels of FT4 were lower in the selenium group compared to the placebo (14 vs. 17 pmol/l group, p = 0.01). Similar results were observed also at 36 weeks (15 vs. 18 pmol/l, p = 0.01). In accordance, the TSH levels increased more in the selenium group at 18 weeks (0.05 vs. 0.02 mIU/l, p = 0.04)
Leo M. et al. (3)	J Endocrinol Invest 2017	Prospective, placebo-controlled, clinical trial	Thirty consecutive patients with untreated GH were randomized to receive Methimazole plus Selenium vs methimazole alone for 3 months	L-seleno-methionine (166 μg daily orally)	No beneficial effect on GH. Administration of Methimazole leads to the normalization of FT3 and FT4, with no difference between groups. Serum levels of malondialdehyde, a marker of oxidative stress, was similarly high in the two groups and decreased significantly after therapy, with no difference between groups. The results suggested that selenium had not significant effect on short-term control of hyperthyroidism
Kahaly GJ. et al. (54)	J Clin Endocrinol Metab. 2017	Prospective, placebo-controlled, clinical trial	Sixty-one consecutive patients with untreated GH were randomized to receive Methimazole plus Selenium or methimazole alone for 6 months	Sodium selenite (300 μg daily orally)	No beneficial effect on GH. The response to treatment, in terms of thyroid function normalization of thyroid hormones, was very similar in the two groups at week 24. During a 12-week follow-up, GH relapsed in 48% of patients included in the selenium group and in 44% of patients of the placebo group. Serum concentrations of Selenium and selenoprotein P were unrelated to response or recurrence rates. At week 36, 12 of 29 patients (41%) and 15 of 33 patients (45%) were responders and still in remission in the selenium and placebo groups, respectively.