[The present status of I-131 therapy for Graves' hyperthyroidism in Japan (survey by questionnaire)]

A survey on the I-131 therapy of Graves' hyperthyroidism was undertaken by questionnaire in 1,246 hospitals of Japan. One thousand and ninety seven of them (88.0%) responded to the questionnaire. In this paper, we report the results and analysis of the replies to the questionnaire. In the 121 hospitals (11.03%) of the respondents, I-131 therapy is being performed for Graves' hyperthyroidism. A gradual increase was observed in the annual number of I-131 treated Graves' disease patients during the period of 1998-2001, from 1,740 to 2,484. I-131 treatment was selected mainly for the cases with side effects from antithyroid drug (ATD) therapy, followed by the cases with complication of heart or hepatic diseases, recurrences of hyperthyroidism after surgery, radioiodine treatment, and long-term ATD treatment. The 41% of respondents used I-131 in order to restore euthyroidism, 34% aimed for hyperthyroidism and 41% used the dose properly between the two according to the patients. Administration dosage of I-131 was estimated mainly on the basis of thyroid uptake and volume in 93% of the respondents and 48% calculated the radiation dose by also determining the effective half-life in the thyroid gland. Thyroid size was estimated by scintigram (51%), US (33%), CT (22%) and palpation (12%). ATD treatment was used before I-131 administration by 70% of the respondents and 34% after radioiodine therapy. A low-iodine diet was given to the patients for a week (46%) or two weeks (47%) before I-131 administration. However, after treatment only 46% of the respondents continued low-iodine diet for a week.