Effect of additional selenium on the levels of serum thyroid peroxidase antibody in patients with Graves disease treated with ¹³¹I

Objective: To explore the effect of additional selenium on the serum levels of thyroid peroxidase antibody(TPOAb) after treatment of Graves disease with ¹³¹I. Methods: A total of 266 patients with TPOAb levels between 10 and 1300 IU/ml participated in this study. TPOAb levels within 10 IU/ml to 60 IU/ml were considered negative, and levels greater than 60 IU/ml were considered positive. All patients were randomly divided into control(n = 112) and selenium treatment group(n = 154). After treatment with ¹³¹I, the control group received conventional therapy, whereas the selenium treatment group received additional selenium(100 kg twice a day). The TPOAb levels and positive ratios of the two groups were compared with pre-therapy levels after treatment for 6 and 12 months. Results: After 6 months, the TPOAb levels in both groups significantly increased compared with the pre-therapy levels(control group: Z = -2.084, P < 0.05; selenium treatment group: Z = -2.112, P < 0.05). However, no significant difference existed in the TPOAb levels between the two groups(Z = -0.764, P > 0.05). After 12 months, the TPOAb levels in the control group did not change significantly compared with the pre-therapy levels(Z = -1.538, P > 0.05), whereas the TPOAb levels in the selenium treatment group significantly decreased compared with the pre-therapy levels(Z = -5.465, P < 0.01). The difference between the two groups were statistically significant(Z = -2.180, P < 0.05). The positive ratios of TPOAb for both groups did not change significantly 6 or 12 months after ¹³¹I therapy(control group: χ₁² = 0.720, χ₂² = 0.103, both P > 0.05; selenium treatment group: χ₁² = 0.023, χ₂² = 0.340, both P > 0.05). Overall, the positive ratios were not statistically significant between the two groups(χ₁² > 0.001, χ₂² = 0.366, both P > 0.05). Conclusions: Additional treatment with selenium after ¹³¹I therapy for Graves disease can effectively decrease the TPOAb levels, especially for patients with high initial TPOAb levels. (authors)