Effect of radioiodine therapy on thyroid nodule size and function in patients with toxic adenomas.
BACKGROUND
Autonomously functioning toxic adenomas are a common cause of hyperthyroidism. Although 131I seems to be a good therapeutic option with little postablative hypothyroidism for these patients, only a small number of recent studies have objectively evaluated changes in nodule size by ultrasonography following radioiodine therapy.


METHODS
We prospectively followed 39 patients with a mean age of 51.2 (35-75) years for 12 months and the patients who remained toxic thereafter, until euthyroidism was provided. Thyroid function tests, sonographic volumes were determined initially and 3, 6 and 12 months after treatment. Radioiodine doses of 3.7 MBq.g(-1) thyroid tissue corrected to a 100% 24 h 131I uptake were given. Thirty patients received a single dose, two required two doses and three required three to five doses of 131I due to persistent thyrotoxicosis. Sonographic volumes of the diffuse parts of the glands decreased significantly by 18% from a mean+/-SD value of 50+/-27.6 ml to 41+/-27.4 ml by the end of the 12 months. A significant decrease (8.3%, P=0.002) was achieved in the first three months. Toxic adenomas decreased in size more efficiently (54%) from a mean of 26+/-24 ml to 12+/-10 ml during 12 months, but also most significantly (28.8%, P=0.003) in the first 3 months of the follow-up. Thirty of the patients (76.9%) became euthyroid at the end of 12 months of follow-up. Four patients (10.3%) became overtly hypothyroid during the follow-up.


CONCLUSIONS
Single or multiple doses of radioiodine can successfully treat toxic adenomas with a low rate of hypothyroidism and considerable nodule-volume reduction.
Erdoğan
Murat Faik
MF
Departments of Endocrinology and Metabolism, Ankara University Medical School, Turkey. murat.erdogan@temd.org.tr
Küçük
Nuriye Ozlem
NO
Anil
Cüneyd
C
Aras
Sevgi
S
Ozer
Diğdem
D
Aras
Gülseren
G
Kamel
Nuri
N
D000236:Adenoma / Q000150:complications / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D011879:Radiotherapy Dosage; D016606:Thyroid Nodule / Q000150:complications / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D013971:Thyrotoxicosis / Q000000981:diagnostic imaging* / Q000209:etiology / Q000532:radiotherapy*; D016896:Treatment Outcome; D014463:Ultrasonography
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals