THERAPEUTIC STUDIES IN HYPERTHYROIDISM: SODIUM 5-IODO-2-THIOURACIL*

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Abstract
Twenty-six cases of hyperthyroidism were treated with iodo-thiouracil in doses varying from 50 to 800 mg. daily. In 21, the drug was given as preparation for surgery; in 3, as an adjunct to radioactive iodine therapy; and in 2, as long-term medical therapy. The maximal clinical response was obtained within 8 days in 10 cases, within 16 days in 7 cases, and within 22 days in 5 cases. In 4 patients response was either slower or incomplete. The optimal dose, as an initial dose for medical management or as preparation for surgery, is between 200 and 400 mg. daily. Further increase of the dose does not improve therapeutic response. Fifty mg. was the medical maintenance dose. Dosage of 600 mg. per day in one case, produced mild leukopenia and granulocytopenia. No other side effects were encountered. Fifteen of the patients had thyroidectomies. At the time of surgery, 10 of the glands were firm and avascular with mean acinar cell heights of below 10 [mu] and 1 was firm and avascular with a mean acinar cell height of 11.2 [mu]; the microscopic picture showed avascularity, follicles with good colloid, a few isolated hyperplastic foci, very little lymphoid tissue, and a tendency toward normal appearance. The other 4 glands were friable and vascular and on examination showed mean acinar cell heights above 11.6 micra; the microscopic study demonstrated follicles with good colloid, but there was an increase in isolated hyperplastic foci and some lymphoid tissue. The glands did not increase in size during treatment. Chemical analysis of the surgical specimens from 9 patients showed an average total I content of 39.1 mg. % with an average protein-bound I content of 22.0 mg.%. In this small series, iodo-thiouracil showed an effective antithyroid action and no goitrogenicity.