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During 30 yr of iodine prophylaxis endemic goiter in school children had disappeared in the Savonlinna area which has been the location of continuous surveillance in the East of Finland. In adults goiter is still found to some extent especially in older people. The iodine intake has increased from about 50 to 300 micrograms per day during these yr and the thyroidal uptake of radioactive iodine has decreased from over 60% to between 20 and 30%. However, there is a significant difference in this regard between nongoitrous individuals and goiter patients. In the present study comprising only goiter patients it was found that the thyroidal uptake was significantly higher in the group of patients with a subnormal response to TRH. These patients also had larger goiters and more palpable thyroid nodules than those with a normal response to TRH. The mean age was significantly higher (60.3 yr) as compared to that in the group which had a TSH-response to TRH of greater than 20 mU/l, smaller glands and less thyroid nodules (45.1 yr). The data fit well with the reports on increasing autonomy with increasing age in nontoxic goiter.

The thyroid proteins and iodocompounds were analysed in the thyroid tissue of 4 patients with nontoxic goitre. Subtotal thyroidectomy was performed for tracheal compression. The thyroid components were labelled with a trace amount of 125I before operation. One patient had congenital goitre and hypothyroidism with cretinoid features. Three other patients belonged to the same family. Two had congenital goitre, one of them with subclinical and biochemical hypothyroidism. There was a range of thyroglobulin (TG) deficiency ranging from virtual absence of TG in the most affected patient to 17% of normal in the least affected one. There seemed to be an inverse relationship between TG content and clinical signs. Also with decreasing TG more iodocompounds were found in the 3-8 S region on gradient centrifugation. In the most affected patient all the radioactivity was in the 3-8 S region, in the least affected one it was all found in the 19 S and 27 S regions. The other patients had an intermediate pattern. The 3-8 S fraction contained albumin, IgG and some material which reacted like TG on immunoelectrophoresis except for the least affected patient. The iodine content was normal whereas the iodination of TG was low-normal or low. Iodotyrosines and iodothyronines were found in all glands analysed on column chromatography but only in the most heavily affected patient did the ratio iodotyrosines/iodothyronines seem to be elevated. Evidently TG was not necessary for hormone formation in this gland but the efficiency of the matrix seemed not to suffice for normal hormone production.