Prognostic Significance of Serum Thyroglobulin Levels and Clinical Factors in Assessing the Efficacy of Radioiodine Therapy in Patients With Hyperthyroidism

Introduction: Radioactive iodine (I-131) has been used for decades as a definitive treatment for hyperthyroidism. However, therapeutic response in clinical practice varies considerably among patients. Objective: This study aimed to evaluate whether pre-treatment serum thyroglobulin (Tg) levels, patient age, and duration of disease could predict treatment outcome. Methods: A prospective study was conducted on 146 patients with confirmed hyperthyroidism (Graves’ disease, toxic multinodular goiter, or toxic adenoma). Treatment outcome (euthyroidism, hypothyroidism, or persistent hyperthyroidism) was assessed six months after I-131 administration and analyzed using multinomial logistic regression. Results: Successful treatment was achieved in 118 of 146 patients (80.82%), while hyperthyroidism persisted in 28 patients (19.18%). Each one-unit increase in Tg raised the odds of treatment failure by 1.004 (p < 0.05). Each additional year of age increased the risk by a factor of 1.09 (p < 0.05), and each additional year of disease duration increased the risk by 1.28, though this did not reach statistical significance (p = 0.06). Conclusion: Pre-treatment thyroglobulin level and older age are independent and statistically significant predictors of poorer outcome, while longer disease duration showed a trend toward significance (p = 0.06). Patients with elevated Tg levels and a prolonged disease history may warrant consideration for higher initial radioiodine activity, pending further validation.