IODINE METABOLISM IN SURVIVING THYROID SLICES FROM PATIENTS WITH EXOPHTHALMIC GOITER*

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Abstract
Surviving slices of hyperplastic thyroid tissue from 18 patients with exophthalmic goiter prepared for operation with strong iodine solution (Lugol''s solution), and of normal thyroid tissue from 4 euthyroid patients were incubated with a solution of Krebs-Henseleit bicarbonate medium and radioiodine by a gravity-flow method. Iodine metabolism in the hyperplastic tissue differed from that of normal tissue in three respects 1) the pattern of I131 uptake in hyperplastic tissue was curvilinear with respect to time, whereas that of normal tissue was rectilinear; 2) iodine transport was greater in hyperplastic tissue than in normal tissue; and 3) the mean proportion of I131 bound to protein was less in hyperplastic tissue than in normal tissue. In both hyperplastic and normal tissue, binding of I131 to protein was blocked by 10"3 M methimazole (Tapazole). In the presence of methimazole, the accumulated radioiodine was discharged, but not completely, by 0.2 M thiocyanate. Thyroid-to-medium ratios of less than unity resulted. Although certain concentrations of inorganic iodide inhibited both I131 trapping and protein binding, organic iodide compounds (thyroxine, triiodothyronine, diiodotyrosine and thyroglobulin) had no effect on either the trapping or the binding function of exophthalmic goiter tissue.