Table 1.
The essential characteristics of the included studies.
| Study | Documents (Sample Size) |
Research Object | Intervention Measures | Main Report Outcome * | Quality Assessment Tool | Main Results | |
|---|---|---|---|---|---|---|---|
| Intervention Group | Control Group | ||||||
| Wichman 2016 [21] | 16(1494) | AIT | Selenium alone or in combination with LT4 | Blank control/placebo alone or in combination with LT4 | ①②⑦⑧ | CCRBT | In the LT4-treated population, TPO-Ab and Tg-Ab levels in the selenium group decreased after 3, 6, 12 months, and 12 months, respectively; in the non-LT4-treated population, TPO-Ab and Tg-Ab levels in the selenium group decreased after 3 months. It still needs to be demonstrated whether these effects were associated with clinical measures. |
| van Zuuren 2013 [13] | 4(463) | HT | Selenium alone or in combination with LT4 | Blank control/placebo alone or in combination with LT4 | ①⑥⑧ | CCRBT | The evidence regarding the efficacy of selenium supplementation in patients with HT was insufficient. |
| Fan 2014 [15] | 9(797) | AIT | Selenium alone or in combination with LT4 or methimazole | Blank control/placebo alone or combined with LT4 or methimazole | ①②⑥⑧ | Jadad scale | Selenium supplementation was related to the significant decrease in TPO-Ab levels at 6 and 12 months; at the same time, the Tg-Ab levels could decrease at 12 months. After selenium supplementation, patients had an increased probability to improve their mood without obvious adverse events. |
| Toulis 2010 [22] | 6(339) | HT | Selenium alone or in combination with LT4 | Placebo alone or in combination with LT4 | ①⑥⑦⑧ | None | Selenium supplementation was linked to a significant reduction in TPO-Ab levels at 3 months, as well as an improvement in mood and/or general wellbeing. |
| Zuo 2021 [2] | 17(1911) | AIT | Selenium alone or in combination with LT4 or methimazole | Blank control/placebo alone or combined with LT4 or methimazole | ①②③④⑤ | CCRBT | Selenium-containing medications demonstrated effectiveness in treating AIT patients and significantly reduced the levels of TPO-Ab in AIT patients. TSH and TG-Ab had no notable difference between the selenium and control group. |
| Qiu 2020 [23] | 23(2394) | AIT | Selenium alone or in combination with LT4 | Blank control/placebo alone or in combination with LT4 | ①②③⑦⑧ | CCRBT | In the LT4-treated population, TPO-Ab and Tg-Ab levels in the selenium group decreased after 3, 6, 12 months, and 12 months, respectively; in the non-LT4-treated population, TPO-Ab levels in the selenium group decreased after 3 and 6 months and Tg-Ab levels decreased after 3 months. Based on the current evidence, there was insufficient justification for the new use of selenium supplementation in the treatment of AIT. |
* Main report outcome ① TPO-Ab; ② Tg-Ab; ③ TSH; ④ FT3; ⑤ FT4; ⑥ mood/wellbeing; ⑦ Immunomodulatory effects; ⑧ Adverse effects. Abbreviations: AIT, Autoimmune thyroiditis; HT, Hashimoto’s thyroiditis; LT4, levothyroxine; CCRBT, Cochrane Collaboration risk of bias tool; TPO-Ab, thyroid peroxidase antibody; TG-Ab, thyroglobulin antibody.