Studies on the Production of High Radioiodine Uptake Goiter with Propylthiouracil

Abstract

Rats were fed a low iodine diet with propylthiouracil added at a level of from 2×1O⁻⁵ to 15×lO⁻²%. In 2 of the 3 experiments, half the animals received supplementary iodine. In no instance was the thyroid enlargement in propylthiouracil-fed rats significantly greater than that of the respective controls without a concomitant lowering of radioiodine uptake. Iodine supplementation favored the formation of diiodotyrosine and T₄ over monoiodotyrosine and T₃. Propylthiouracil inhibited formation of diiodotyrosine and T₄ to a greater extent than it did monoiodotyrosine and T₃. Supplementary iodine decreased goitrogenesis but increased the inhibitory effects of propylthiouracil on radioiodine uptake and on formation of diiodotyrosine and T₄.