Therapy of endemic goitre: controlled study on the effect of iodine and thyroxine

Two kinds of medical treatment of endemic goitre (400 microgram of iodine, n=11, and 150 microgram of L-thyroxine, n=12) were compared in a double blind study with a placebo group (n=12) during a period of 12 months and an observation time of three months after cessation of therapy. The means of the neck circumference and of the estimated thyroid volume decreased significantly during treatment in both groups, whereas no significant difference was observed in the placebo group. The results in both therapy groups did not differ significantly from each other. No side effects or symptoms of hyperthyroidism were observed. During treatment the index of free thyroxine (FT4I) increased significantly in both the iodine and the thyroxine group and delta TSH after TRH decreased significantly. Total triiodothyronine (TT3) did not show significant alterations. Three months after cessation of therapy in the thyroxine treated group the mean FT4I dropped into the range before treatment, whereas it remained slightly elevated in the iodine group. In the thyroxine treated group the mean delta TSH was higher than its value before therapy. After withdrawal of iodine, however, the mean delta TSH remained decreased for three months. The study indicates that 400 micrograms of iodine per day may be at least as effective as a standard dose of 150 micrograms of thyroxine to treat endemic goitre in an iodine deficient area.