Hypothyroidism after treatment with Bamethasemol in Iran, Comparison of the Effect of Methimazole in Tehran and Boston

The response tomethimazole(l-methyl-2-mercaptoimidazol,MMl) therapy was evaluated in 18 patients with diffuse toxic goitre residing in an area of iodine deficiency(Tehran)and in 18 such patients residing in an area of iodine sufficiency(Boston) .Free T4 index(FT4I) decreased from 22.9± 4.8 to 4.9± 4.3 in Tehran and from 23.8± 5.2 to 17.0±4.1 in Boston, 4 weeks after administration of MMl 10 mg three times daily. Free T3 index(FT3I) decreased from  489±124 to 117±58 in Tehran and from 512±250 to 368tl52 in Boston. in patients residing in Tehran,FT4r was normal in 9( (6.3 in 6), above normal in one,and subnormal in 8(44%9four weeks after such therapy.In 4 of 8 patients with subnormal FT4I,serum TSH was also above normal and clinical findlngs of hypothyroidism were evident. These results indicate that treatment with recommended textbook .doses of MMl causes hypothyroidism in patients residig in Tehran, an area of iodine deficiency. Furthermore,they support the hypo­thesis that dosage of thionamide compounds and duration of their initial high doses necesaary to induce euthyroidism may vary in various parts of the world.