Endocrine Abstracts

Background: The Royal College advises 500–800 MBq of Radioiodine(RAI) for toxic multinodular goitres (MNG), and 400–800 MBq RAI for euthyroid MNG. In our institution, a standard low dose of 370 MBq has traditionally been given to all patients with benign thyroid disease. This audit examined whether outcomes are optimal with low dose therapy, and whether a variable dose protocol should be adopted.

Patients and Methods: We analysed 49 patients at the NNUH who had received RAI for MNG from 2008 to 2010. 42 female, 7 male patients were treated, age range 44–88 yrs. 24 patients were thyrotoxic and 10 patients had subclinical hyperthyroidism. The indications for RAI in the 15 euthyroid patients were large retrosternal goitres, tracheal compression, dysphagia and an increasing size. 35 patients received 370 MBq, 3 600 MBq and 11 800 MBq.

Results: 88% patients presenting with a suppressed TSH showed a biochemical response after a single dose of 370 MBq: 68% TSH normalised, 20% were rendered hypothyroid. Of 26 patients presenting with large goitres or obstructive symptoms. appreciable shrinkage was documented in 76% and relief of compression symptoms was documented in 72% within 6 months. However, 3 of this group received 600 MBq and 11 received 800 MBq. No patients reported an increase in goitre size following treatment. 2/15 patients who were euthyroid pre RAI were rendered hypothyroid post treatment (13% of this group, 18% total).

Conclusions: Low dose RAI treatment is effective at treating MNG associated thyrotoxicosis, with low rates of early hypothyroidism. Compression symptoms also responded well to RAI treatment in this series, although the doses administered were larger. We propose that a standard low dose 370 MBq treatment is effective and well tolerated for small MNG with clinical or subclinical thyrotoxicosis. However, a standard dose of 800 MBq will now be adopted in this institution for large goitres and patients with obstructive symptoms.

Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.