ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2011) 25 P315

Outcomes of radioactive iodine treatment for hyperthyroidism: 1 year follow up survey in subjects attending a general hospital endocrine clinic

Rajesh Rajendran, Ramona Verdaguer & David Coppini


Poole General Hospital, Poole, UK.


Aim: Retrospective survey on outcomes of 131I therapy in subjects with hyperthyroidism.

Methods: We analysed the outcomes at 1 year, of 55 episodes of 131I therapy in 52 patients (36 males, 15 females) who were treated between January 2007 and January 2009.

Results: At 1 year post 131I therapy, 31 (56.3%) subjects were hypothyroid (median age 54 years), 14 (25.5%) were euthyroid (median age 69 years) and 10 (18.2%) remained hyperthyroid (median age 73 years). 31 subjects (56.3%) had Graves’ disease, 20 (36.4%) had mutlinodular goitre (MNG) and 4 (7.3%) were not classified.

In 39 female subjects treated with 131I, 22 (56.4%) became hypothyroid, 10 (25.7%) remained euthyroid and 7 (17.9%) became hyperthyroid. Amongst the 16 male subjects, 9 (56.2%) became hypothyroid, 4 (25%) remained euthyroid, and 3 (18.8%) became hyperthyroid.

Out of 31 subjects who became hypothyroid, 21 (67.8%) had received 350 MBq, 9 (29%) had received 550 MBq and 1 (3.2%) had 650 MBq. Out of 14 subjects who were rendered euthyroid, 5 (35.7%) had 350 MBq, 8 (57.1%) had 550 MBq and 1 (7.1%) had 620 MBq. In the 10 subjects who remained hyperthyroid after 131I therapy, 5 (50%) had received 350 MBq and 5 (50%) had 550 MBq.

Thirteen subjects became profoundly hypothyroid (TSH>50) within one year. Of these, 10 (77%) had Graves’, 2 had MNG (15%) and 1 (8%) was not classified. 7 subjects (54%) had received 350 MBq whereas 6 (46%) had received 550 MBq of 131I therapy.

Conclusions: Despite the relatively small sample size, age, sex, aetiology and dose of 131I did not seem to influence the outcome of 131I therapy. Although larger studies are needed to confirm our observations, our series suggests an increased risk of profound hypothyroidism following 131I in subjects with Graves’ disease when compared to subjects with MNG.

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