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In spite of being used for more than 50 years in the treatment of
benign thyroid disorders, a number of questions remain (Table 5).
In the toxic patient, further studies are needed in order to reach a consensus on patient selection criteria and on the adequate investigations before offering 131I-therapy. In these patient categories, randomized studies on effects and side-effects as well as cost-benefit comparing ATD, 131I, and surgery in prospective randomized trials are still needed. Further studies on the optimum dose calculation should be encouraged. The influence of pre- and post treatment with ATD on the effect of 131I should be studied. Although generally considered safe in the adult population, further studies on which is the lower age limit of treatment and whether large 131I doses, given to e.g. patients with monstrous goitre, are also safe, are needed. In the non-toxic patient, additional studies are warranted in order to clarify which patients are best suited for 131I-therapy. Much work is needed before a consensus can be reached on adequate pretreatment investigations. Should fine needle biopsy routinely be performed? Should serum calcitonin be determined? To name but a few of the pressing questions. Randomized studies comparing L-T4, 131I and surgery are needed, as are studies on the optimum 131I dose calculation for treatment of various types of non-toxic goitre. The most recent reports suggest that side-effects are in no way negligible (hypothyroidism, radiation thyroiditis, insufficient effect) and further long-term follow-up data in larger groups of patients are awaited. Whether the risk of thyroid and non-thyroid malignancy is as low as in toxic goitre cannot be answered before much larger groups of patients have been followed for several decades. While searching for preventive measures and awaiting treatment modalities, for toxic as well as non-toxic goitre, of a less destructive and a more physiologic nature, I hope that many colleagues will take on these and other challenges in order to optimize 131I-therapy in benign thyroid disorders. Little is known about effects and side-effects of 131I-therapy in this type of patient. If a dose is given, calculated according to that given for toxic solitary nodules,25,26 it is likely that the consequences of treatment are also similar (Table 4). Indeed, a short-term study suggests thyroid volume reduction to be similar26. Frequency of hypothyroidism depends on serum TSH level, thyroid autoantibody status and on degree of extranodular thyroid tissue uptake. Autoantibody positive subjects are more prone to develop hypothyroidism27 as are subjects with measurable TSH and evidence of extranodular uptake. |
