Comparison of Outcome in Radioiodine Induced Euthyroid and Hypothyroid Patients

T he major consequence of radioiodinetherapy for thyrotoxicosis is hypothyroidismand long-term precise managementof hypothyroidism may beproblematic. In this study, the long-term outcomeswere compared in radioiodine treatedeuthyroid and hypothyroid patients on thyroidhormone treatment.Materials and Methods: One hundred and thirtyeight patients with diffuse toxic goiter weretreated with radioactive iodine. One hundredand seven patients (78%) returned for follow upvisits for up to 11.5±O.8 years. Numbers of occurrencesof thyroid dysfunction in each patientwere recorded and a total cost of managementwas calculated.Results: At the end, 41 patients (38% ) were stilleuthyroid (group 1) and 66 (62%) became hypothyroid(group 2). Serum, FT4, FT3, TSH, thyroidantibodies, lipid profile, calcium, phosphorus,and PTH were measured and bone mineral density,ECG and echocardiography were performed.There was no significant difference inage, sex, duration of symptoms and thyroid functionbetween the 2 groups. The cost of treatmentwas lower in group 1 than in group 2. During11.5 years of follow up, percentage of elevatedand suppressed TSH in groups 1 and 2 were 0.02and 20.5, p O.OOl and 7.9 and 13.4, p O.OOl, respectively.At the end of 10 years, goiter rate, se-rum T4, T3, thyroid antibodies, lipids, Ca, P andPTH and bone mineral density and echocardiographydata were not signifanctly different betweentwo groups. However, mean serum TSHand number of TSH above 5 mUfL was greater ingroup 2 than 1 (p O.Ol).Conclusion: It is concluded that thyroid derangementsfrequently occur in patients who becomehypothyroid after radioiodine therapy,while on replacement therapy.