Efficacy of selenium supplementation for patients with Graves' hyperthyroidism during methimazole treatment: protocol for a systematic review and meta-analysis

Introduction The most common cause of hyperthyroidism, Graves' disease is a common organ-specific autoimmune disease. Selenium is an essential trace element of the human body that is mainly concentrated in the thyroid gland and is involved in the synthesis and metabolism of thyroid hormones. Most studies have shown that the level of selenium is closely related to the occurrence and development of thyroid diseases, and selenium supplementation can help improve thyroid function. This study aims to evaluate the efficacy of selenium supplementation for patients with Graves' hyperthyroidism during methimazole treatment.Methods and analysis We will search the electronic databases including PubMed, Web of Science, Embase, the Cochrane Library, China National Knowledge Infrastructure, Wanfang Data and Chinese Biomedical Literature, and the time was deadline to December 2023. To evaluate the efficacy of methimazole combined with selenium supplementation in the treatment of Graves' hyperthyroidism, randomised controlled trials will be included. The Cochrane Collaboration's risk of bias tool will be used to assess the quality of all included studies, and the baseline data of all the studies are extracted by the authors. A random-effects model or a fixed-effects model is used to analyse the outcomes. The primary outcomes are the levels of selenium, triiodothyronine, free thyroxine and thyroid-stimulating hormone (TSH), whereas the secondary outcomes include TSH receptor antibody, thyroid peroxidase antibody and thyroglobulin antibody.Ethics and dissemination Ethics approval is not required since no original data will be collected. The results of this study will be published in a peer-reviewed journal.PROSPERO registration number CRD42023410999