ACUTE CHANGES IN THYROID VOLUME AND FUNCTION FOLLOWING I-131 THERAPY OF MULTINODULAR GOITER

OBJECTIVE Many textbooks claim that radioiodine (I-131) treatment should be given with care to a goitre with substernal extension, for fear of acute swelling of the gland and thus respiratory problems. Since I-131 is used increasingly in the treatment of non-toxic as well as toxic goitre we have evaluated the acute changes in thyroid volume following I-131 therapy. DESIGN Evaluation of potential acute changes In thyroid volume and function after I-131 treatment in patients with non-toxic goitre treated because of compression symptoms or for cosmetic reasons, as well as in patients with toxic goitre. PATIENTS Out-patients with multinodular goitre, either non-toxic (n=20) or toxic (n=10). Excluded were patients with a substernal goitre. MEASUREMENTS Ultrasonically determined thyroid volume and standard thyroid function variables were investigated before and 2, 7, 14, 21, 28 and 35 days after treatment. RESULTS in non-toxic goitres the thyroid volume did not increase significantly, the maximum increase in the median volume being 4% on day 7. Serum levels of free T3 and free T4 indices increased by 20% (day 7) and 13% (day 14) (P = 0.002), respectively. Likewise thyroid volume in toxic nodular goitre did not change significantly after I-131 treatment (maximum median increase was 2%). None of the patients presented symptoms of tracheal compression. CONCLUSIONS I-131 treatment of non-toxic as well as toxic multinodular goitre does not seem to increase thyroid volume.