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

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.

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.

Out-patients with multinodular goitre, either non-toxic (n = 20) or toxic (n = 10). Excluded were patients with a substernal goitre.

Ultrasonically determined thyroid volume and standard thyroid function variables were investigated before and 2, 7, 14, 21, 28 and 35 days after treatment.

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.

131I treatment of non-toxic as well as toxic multinodular goitre does not seem to increase thyroid volume.