Treatment of Hyperthyroidism With Sodium Iodide I 131

The incidence of hypothyroidism among 848 patients treated for hyperthyroidism with sodium iodide I 131 has been compared with the incidence among 121 patients treated for hyperthyroidism surgically. During follow-up periods ranging from less than a year to 16 years, at least 51% of those treated with sodium iodide I 131 and 28% of those surgically treated became hypothyroid. After the first year of follow-up study, the cumulative incidence of hypothyroidism increased 2.8% per year in the group treated with the radioactive compound and 1.7% in the group surgically treated. It is also estimated that within the first ten years after treatment, 70% of the group treated with sodium iodide I 131 and 43% of the group surgically treated will have become hypothyroid.