[Results of radioiodine treatment of autonomous thyroid adenomas taking into consideration regional iodine kinetics and paranodular uptake].

In 110 patients with autonomous adenoma of the thyroid, the success rate of therapy with radioiodine using different local dosages (300 and 400 Gy) was monitored. Furthermore the relative paranodular uptake before and after radiotherapy was compared in dependence on the duration of therapy. In a short period of therapy (5-8 d) the paranodular uptake decreases as compared to a long duration (9-20 d) where it increases. This explains the higher rate of hypothyroidism found in the group of patients with a longer period of therapy. The success rate was 93.6% after applying a dosage of 300 Gy and 95% after 400 Gy. However we found a slightly smaller incidence of hypothyroidism (3.2%) after 300 Gy as compared to 400 Gy (8.8%). Nevertheless the higher dosage should be chosen to reduce the failure rate. Because of the increased rate of hypothyroidism with increasing paranodular uptake it is recommended in cases with uptake ratios between 10 and 20% (so-called transitional type) to induce exogenic suppression of the paranodular tissue by means of thyroid hormone.