THE EFFECTS OF SODIUM IODIDE, 6-PROPYLTHIOURACIL, AND l-METHYL-2-MERCAPTOIMIDAZOLE DURING RADIOIODINE THERAPY OF HYPERTHYROIDISM*†

RADIOACTIVE iodine (I131) is now well established as an agent in the therapy of Graves' disease (1—6). One disadvantage in its use has been a latent period of four to eight weeks between administration of the isotope and consequent clinical effect. The need for a study of the usefulness of antithyroid agents in obtaining earlier control over toxicity during this interval has been indicated from the work of others (2, 3, 7, 8). The present report deals with the results from sodium iodide, 6-propylthiouracil, and l-methyl-2-mercaptoimidazole1 given for a short period following I131 therapy. Eighty adult patients with unquestioned toxic diffuse goiter, selected at random, were treated by one of four methods: Group I received only radioiodine, I131, in therapeutic doses; Group II, the isotope and sodium iodide; Group III, the isotope and 6-propylthiouracil; Group IV, the isotope and l-methyl-2-mercaptoimidazole. Radioiodine dosage was determined by one of us (S.C.W.) for all patients. Essentially, the degree of toxicity and size of the thyroid-gland were the factors from which dosage was estimated. Radioiodine uptake was measured directly over the thyroid gland at twenty-four hours, as described elsewhere (1). The effective half-life of the I131 within the gland was determined from weekly measurements over the gland for four weeks following therapy (1, 9).