One of the highlights of the therapeutic advances in the field of thyroid-related diseases in 2011-2012 is the treatment of mild thyroid ophthalmopathy with sodium selenite. This disease has been a worldwide challenge, especially in patients with mild to moderate, unmet indications for hormone use (patients with underactive ophthalmopathy), and there is no recommended and definitive treatment. This advance came from a paper published in 2011 in the world’s most prestigious journal, the New England Journal of Medicine (which for many years was ranked number one in overall global journal ratings by industry and is considered a guidepost for clinical use by medical practitioners worldwide), on sodium selenite for mild thyroid proptosis, suggesting that the assessment of ocular self-symptoms in patients treated with sodium selenite was superior to that of the placebo group. In February 2013, a British academic study found that serum selenium concentrations were lower in patients with hyperthyroid Graves’ disease than in the normal population, and a previous small clinical study found that selenium preparations in combination with antithyroid drugs promoted faster attainment of thyroid hormone levels. Mechanism of sodium selenite in the treatment of thyroid synostosis: The pathogenic mechanisms of thyroid synostosis are currently thought to include cytokine activation, immune response, and oxidative stress. Selenium is an antioxidant stress trace element, and improving the local oxidative and antioxidant balance in the peripheral tissues of the eye is likely to be the mechanism for the treatment of hyperthyroidism proptosis. Possible long-term side effects of sodium selenite application: The United States conducted a survey of blood selenium concentrations in the entire population back in the late 1900s and found that the entire population was low. A large scale intervention study of selenium supplementation for tumor prevention in the population was conducted, and in this intervention (up to 12 years) it was only found that selenium supplementation caused an increased risk of developing diabetes, especially in people whose baseline blood selenium levels were at the high limit of normal. This suggests that the safety of selenium preparations is high and that if the indications for their application (baseline serum selenium levels are measured first) are mastered, the potential for increased risk of diabetes with overdosage can be minimized. The current main applications of selenium supplementation in various countries The serum selenium levels in diabetic patients were generally found to be low when measured in large populations, so that appropriate supplementation of blood selenium may be beneficial for the improvement of islet cell function, but there is a lack of very valuable evidence. Patients with various tumors have lower than normal serum selenium levels, and there is evidence that selenium supplementation has preventive and therapeutic value for prostate and lung cancers in populations with low serum selenium, but this needs to be verified in further trials. Testing before applying selenium preparations: Serum selenium is measured before applying sodium selenite, if the blood selenium level is below the midpoint of the normal range, then sodium selenite can be supplemented (the drug is available in China) and the blood selenium level can be monitored for six months to one year. If the blood selenium level is at the high normal line, the trade-off is to see whether to proceed with this treatment (although in previous studies serum selenium was not pre-determined and blood selenium levels were monitored after supplementation).