The effects of oral iodide, levothyroxine and of iodide and levothyroxine in combination were studied in three groups of 30 children, age 13–15 years, with euthyroid goitre. As endpoints of this study, we used thyroid volume reduction, thyroid hormones, thyrotropin and thyroid grey-scale histograms by computerized analysis. The three groups were well matched with respect to mean age, body weight and pretreatment thyroid volumes and thyroid hormones. Mean urinary iodide excretion before treatment was in the range of 30 μg/g creatinine, since the study was conducted in an iodine-deficient area. All three treatment regimens led to significant reductions in thyroid volume within one month. After six months on 100 μg of levothyroxine, thyroid volume had decreased from 14.1±4.2 ml to 8.3±2.6 2.6ml (mean±sd);on 150 μg of iodide, from 18.5±6.2 ml to 8.8±2.7 ml; and on 100 μg of iodide plus 50μg of levothyroxine, from 17.2±3.1 ml to 8.3±2.0 ml. When treatment was discontinued for three months, or the dosage reduced, thyroid volume increased again in the levothyroxine (to 11.3±2.5 ml) but not in the iodide group. Grey-scale values (by ultrasound, computer-aided estimation) after nine months were significantly different between the three treatment groups; no change was observed with levothyroxine, but after 150 μg of iodide as well as after combined treatment with levothyroxine and iodide there were marked decreases of grey-scale values; this is interpreted as reflecting a decrease in follicle size and colloid content of the thyroid which takes place after iodide supplementation. In conclusion, iodide treatment as well as combined treatment with levothyroxine and iodide lead to volume reduction of juvenile goitre which is quantitatively similar but qualitatively superior compared to the effects of levothyroxine alone.

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