Assessment of Clinical Outcomes of Low Dose Radioactive Iodine Therapy in Patients With Hyperthyroidism at Nuclear Medicine Center

Background: Hyperthyroidism is a common endocrine disorder characterized by excessive thyroid hormone production and increased metabolic activity. Radioactive iodine (RAI) therapy is considered one of the most effective definitive treatment modalities for hyperthyroidism. Recently, low-dose radioactive iodine regimens have gained increasing attention because of their effectiveness, safety, and lower radiation exposure. Objectives: To assess the clinical outcomes of low-dose radioactive iodine therapy among patients with hyperthyroidism treated at the Nuclear Medicine Center in Mosul city and to identify factors associated with treatment outcome. Methods: This observational prospective study was conducted at the Mosul Nuclear Medicine Center from August 2024 to January 2026. Eighty-four patients with hyperthyroidism due to Graves’ disease, toxic multinodular goiter, or toxic adenoma were included. Demographic, clinical, laboratory, and ultrasonographic data were collected. Thyroid function tests were evaluated before therapy and during follow-up at 3–6 months and one year after treatment. Clinical outcomes were categorized into euthyroidism, hypothyroidism, or persistent hyperthyroidism. Statistical analysis was performed using SPSS version 31, and a P value <0.05 was considered statistically significant. Results: The study included 59 (70.23%) females and 25 (29.77%) males, with a mean age of 47.12 ± 13.03 years. Graves’ disease represented the most common cause of hyperthyroidism in 42 (50%) patients, followed by toxic multinodular goiter in 38 (45.2%) patients and toxic adenoma in 4 (4.8%) patients. Significant improvement in thyroid function tests was observed after radioactive iodine therapy, with marked elevation of TSH levels and reduction in T3, free T3, T4, and free T4 levels (P<0.001). Patients receiving 20 mCi demonstrated better therapeutic outcomes compared with those receiving 10 mCi, with a statistically significant association between radioactive iodine dose and treatment outcome (P=0.038). Baseline ultrasound findings were also significantly associated with treatment outcome (P=0.027), whereas age and gender showed no significant relationship with therapeutic response. Conclusions: Low-dose radioactive iodine therapy is an effective and safe treatment modality for hyperthyroidism, producing significant biochemical and clinical improvement in most patients. Higher radioactive iodine doses and certain ultrasound characteristics were associated with better treatment outcomes. Individualized dose selection and careful post-treatment follow-up are recommended to optimize therapeutic success.