Acute changes in thyroid volume and function following ¹³¹I therapy of multinodular goitre

Abstract

OBJECTIVE: Many textbooks claim that radioiodine (131I) 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 131I is used increasingly in the treatment of non-toxic as well as toxic goitre we have evaluated the acute changes in thyroid volume following 131I therapy. DESIGN: Evaluation of potential acute changes in thyroid volume and function after 131I 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 131I treatment (maximum median increase was 2%). None of the patients presented symptoms of tracheal compression. CONCLUSIONS: 131I treatment of non-toxic as well as toxic multinodular goitre does not seem to increase thyroid volume.