Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2009) 19 P349

SFEBES2009 Poster Presentations Thyroid (59 abstracts)

The outcome of treatment of relapsed hyperthyroidism with a fixed dose of 550 MBq radioiodine

AS Lewis , T Rea , AB Atkinson , PM Bell , CH Courtney , DR McCance , K Mullan & SJ Hunter

The Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Belfast, UK.

Radioiodine is the treatment of choice for relapsed hyperthyroidism although the optimum protocol is uncertain. We assessed the outcome of therapy with 131I in relapsed hyperthyroidism using a fixed dose regimen.

We retrospectively studied 449 patients (M: F 82: 367; age range 13–89 y, median 42 y) treated between 2003 and 2007 with a fixed dose of 550 MBq 131I for relapsed hyperthyroidism. Patients were classified as either Graves’ disease, toxic multinodular goitre or indeterminate aetiology. Where patients were on antithyroid drugs these were stopped at least 1 week prior to radioiodine.

One year following radioiodine 334 patients (74%) were hypothyroid, 85 (19%) were euthyroid and 30 (7%) had required a further dose of 131I. Patients with Graves’ disease were more likely to become hypothyroid than those with toxic multinodular goitre (78 vs 37%, P<0.001) whereas the latter were more likely to become euthyroid (55 vs 11%, P<0.001). Free T4 >80 pmol/l at presentation was associated with an increased failure rate (17% compared with 5 and 3% for 40–79 pmol/l and <40 pmol/l respectively; P=0.01). Patients with a small/no goitre were more likely to be successfully treated by a single dose of radioiodine (96%) than those with a medium/large goitre (85%, P<0.001). Anti-thyroid medication was taken by 345 patients (77%) (carbimazole n=319) and was associated with an increased failure rate (8 vs 2%, P=0.027).

In conclusion, a single fixed dose of 550 MBq 131I is highly effective in treating relapsed hyperthyroidism. The aetiology, severity of hyperthyroidism, goitre size and prior anti-thyroid medication have a significant effect on outcome.

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