[The importance of the radioiodine test for the calculation of the therapeutic dose in benign thyroid diseases].

The aim of this study was to determine the significance of the radioiodine uptake test for predicting the kinetics of therapeutic 131I doses in the treatment of benign thyroid disorders. We studied retrospectively the histories of 518 consecutive patients treated with 131I for hyperthyroidism or autonomous thyroid goiter, with respect to uptake and effective half-life of tracer and therapeutic doses. The mean half-life and uptake of the therapeutic doses were significantly smaller than that of the tracer dose. A comparison of different methods of calculation showed that the radioiodine uptake test is indispensible for dose calculation in radioiodine treatment but a single measurement after 24 or 48 h is sufficiently accurate because, on average, the therapeutic dose was achieved as planned and with the smallest scatter. Average half-lives specific to the disease to be treated may be used in the calculations.