Possible Interaction: Iodine and Thiouracil

“TSH increased the absolutethyroid uptake of I131; additionally administered iodine and thiouracil depressed it.”

“In the intact rat thiouracil causes the thyroid gland to enlarge, depresses the thyroid accumulation of radioactive iodine , and inhibits the formation of diiodotyrosine and thyroxine (2, 3, 4).”

“The goitrogenic response to thiouracil was much greater when the diet was supplemented with iodine than when the diet was iodine-deficient.”

“It is suggested that both thiouracil and reduction in the environmental temperature inhibit the enzymatic oxidation of iodide to iodine in the gland, while thiocyanate reduces the uptake of iodide by thyroid tissue.”

“However, both thiouracil and ITU produced a small augmentation of exogenous thyrotrophin action, and both increased the biologic decay rate of thyroidal iodine.”

“It was also thought that the concurrent administration of iodine might diminish the hyperplasia and vascularity of the thyroid gland otherwise induced by the thiouracil ; a reduction in the duration of pre-operative treatment would thus be possible and the technical difficulties of excision would be minimized.”

“If the subsequent organic binding of iodine is blocked with thiouracil , the thyroid: serum iodide concentration ratio (T/S) can be determined (Vanderlaan and Vanderlaan, 1947).”

“One of the purposes we hoped to achieve in the synthesis of these … providing an antithyroid drug which might render unnecessary the simultaneous use of iodine … thiouracil as practiced preoperatively in patients with hyperthyroidism, and which might alleviate … defects in thiouracil or in its 6-alkyl derivatives (Christian, 1946).”

“The synthetic combination of iodine and thiouracil1 (Barrett, et al. (4)) raised the possibility that involution to normal histologic structure, prevention of goitrogenicity, and induction of normal physiologic relationship might be accomplished.”

“In Dvoskin’s experiments, the injection of elemental iodine prevented entirely the goitrogenic action of thiouracil given orally or by implantation.”