I-131 treatment of hyperthyroidism. Analysis of 369 cases treated with an initial dose of 15 MC or less.

Patients with hyperthyroidism can be treated by one of the following methods: (1) medical treatment with thiocarbamide, (2) surgical treatment with subtotal thyroidectomy, and (:·n radiological treatment with radioactive iodine (1131). Although each has certain advantages and disadvantages, radioiodine has apparently been used much more frequently in recent years because of its simplicity, safety and economy. The most important and difficult problem in P31 treatment for hyperthyroidism is to determine the appropriate dose for each individual patient. Since the response of a patient to a selected dose varies widely, and a quantity which may restore normal thyroid function in one patient may prove entirely ineffective in another, or may even induce lasting myxedema in a seemingly comparable case. The author started to use P31 for the treatment of hyperthyroidism a tthe National Taiwan University Hospital since 1958. As a rule, the dose for administration was cakulated based on the weight of the gland and 24 hour thyroidal P 31 uptake. The therapeutic dose was aimed to let 100 uc of P31 to be retained in each gram of the gland. But when the calculated dose was too great, a limited dose was given. During the period from September 1959 to December 1961, the level of this limitation was arbitrarily settled at 7 me, and 348 cases were treated with an initial dose of 7 me or less. The result after one dose administration was reported in this journal in 1964 1'. The one-dose cure rate was as follows: 1) 56.5% in the group of patients to whom calculated doses below 7 me were given. 2) 34.6% in the group of patients to whom the limited dose of 7 me was given although their calculated dose was larger. 3) 40.8% in overall patients. This overall one-dose cure rate of 40.8% was considered too low, so that