Functional and Histologic Effects of Therapeutic Doses of Radioactive Iodine on the Thyroid of Man*

THE purpose of this paper is to present observations on the effects of radiation in patients who have been treated with radioactive iodine. Attention has been directed toward: 1) the metabolism of the thyroid cells as measured by tracer doses of radioactive iodine before and after radiation therapy; and 2) the histologic features of cellular damage of the thyroid and the regenerative processes that may take place after large doses of radioactive iodine. It has been adequately shown that a large dose of radioactive iodine impairs the functional capacity of the human thyroid (1–22). This principle has been employed in the treatment of some patients with Graves' disease (1–4, 6, 8, 9, 17–19, 21–35), others with functioning carcinomas of the thyroid (29–35) and still others with heart disease accompanied by normal thyroid function (17, 19, 28). Although a large number of patients with thyrotoxicosis have been treated with radioactive iodine, relatively few observations have been published on the nature of the cellular damage and the regenerative processes that may follow.