REFERENCES 1. Shapiro B. Optimization of radioiodine therapy of thyrotoxicosis: what have

to toxic nodules within the frame of Graves ' disease that cannot. Furthermore, hyperthyroid patients with an increased ITI are more resistant to treatment (3). We also showed that a high IU (>40%) does not exclude iodine excess, nor does a normal urinary iodide, and the PB*I at 24 hr correlates negatively with ITI so that this measurement can be used to predict the iodide stores of the gland (4). Of course, we are aware that the possibilities of measuring ITI are very scarce. Nevertheless, as we estimate that more than 30% of our hyperthyroid population present with iodine excess (espe cially the elderly as they need more radiodine), it is important to recognize some indicators that can be overlooked. Aside from the classical features, such as knowledge of iodine intake, a low IU and an increase of urinary iodide, the following factors should alert the physician to the possibility of iodine excess (at least in areas with relatively low iodine intake): a nonautoimmune toxic nodular goiter with a low PB * I at 24 hr and a suspiciously high T4H3 ratio. Radioiodine treatment should then be adapted ac cordingly