THE EFFECT OF ORAL-ADMINISTRATION OF IODINE TO PATIENTS WITH GOITER AND HYPOTHYROIDISM DUE TO DEFECTIVE SYNTHESIS OF THYROGLOBULIN

The effects of administration of iodine (1 mg/day orally, 64 days) wer e studied in three siblings with congenital goiter and hypothyroidism due to defective thyroglobulin (Tg) synthesis. The patients presented very large goiters, elevated RAI uptake, negative perchlorate discharg e test, low serum T-4, and elevated TSH concentrations. Immunoassayabl e Tg was low and failed to increase after stimulation with exogenous b ovine TSH. Analysis of individual thyroid extracts by gel filtration f ailed to reveal a Tg component; the immunoassayable Tg antigens in the se goitrous tissues were 0.12 and 0.21 mg/g tissue, respectively (norm al 70-90 mg/g tissue). The histological pattern of their thyroids was compatible with defective Tg synthesis. The administration of iodine c aused a rise in the mean serum T-4, T-3, and free T-4 concentrations i n all three siblings, but did not alter the serum Tg concentration. TS H concentrations rose in the terminal period of observation in the thr ee subjects and this was considered to be due to a possible effect pro duced by the iodine load in the thyroperoxidase system (Wolff-Chaikoff effect). One patient showed an increase in goiter size during the per iod of observation. These results suggest that iodine administration e nhanced the ability of the dyshormonogenetic gland to synthesize iodot hyronines.