Predictive factors influencing hypothyroidism following the radioactive iodine treatment of Graves' disease in different periods.

In China, due to the risks of hypothyroidism after radioiodine treatment, radioiodine is not commonly used as a first-line treatment. In this study, factors influencing the development of hypothyroidism after I therapy for Graves' hyperthyroidism were evaluated. This was a retrospective study with a 12-month follow-up. Retrospectively, we investigated 1,264 patients with diagnosed Graves' disease who received I therapy using the Marinelli-Quimby formula. The first three months after I therapy, hypothyroidism risk was higher among patients with lighter thyroid weight, higher levels of thyroglobulin antibody (TGAb), and shorter durations of Antithyroid drug (ATD) treatment before I therapy (P < 0.05). After 6 months, patients with lighter thyroid weight, shorter ATD treatment duration before I therapy, and higher iodine intake showed an increased risk of hypothyroidism. (P < 0.05). After one year, lower 24-h iodine uptake was the only risk factor for hypothyroidism (P < 0.05). Our results show that  I is an effective therapy for GD. Even if over time, the occurrence of hypothyroidism may ultimately depend on the patients' radiosensitivity to I before treatment. But in the first 3 to 6 months or even one year, we can still take measures to effectively improve the quality of life of patients.