The first clinically and biochemically documented case of recurrent thyrotoxicosis after I-131 induced hypothyroidism in a patient with Graves' disease is reported. Two months after the administration of 9.2 mCi of I-131, the subject developed hypothyroidism. One month later, the patient became euthyroid. Then, nine months following ablation, the patient again developed thyrotoxicosis. A second dose of I-131 of 12.5 mCi was required to finally produce permanent hypothyroidism. This case illustrates the recurrence of hypothyroidism after what had seemed to have been adequate I-131 radiation.
* From the Department of Medicine, Division of Endocrinology and Metabolism, Hahnemann University
† From the Department of Nuclear Medicine, Metropolitan Hospital, Philadelphia, Pennsylvania