Radiation, Thyroid Cells and131I Therapy—A Hypothesis

Abstract

The results of I131 therapy are unsatisfactory. Many patients require multiple doses and a large minority ultimately develop hypothyroldism. Accurate and optimal I131 dosimetry is impossible and thyroid cell radiosensitivity may be an important factor in determining the outcome of I131 therapy. These difficulties are re-emphasized and the hypothesis is extended to include the important factors of differential thyroid cell radiosensitivity and cell turnover. Thyroid cell function is reduced by I131 therapy and cell multiplication must be severely impaired, because cell reproductive integrity is much more radiosensitive than cell function. As a result of the latter, thyroid cell renewal is abolished and hypothyroidlsm is the end result of cell depopulation. Current problems of radiation therapy for thyrotoxicosis are discussed in the light of this hypothesis.