Dosimetry-based treatment for Graves' disease.

Steve L. Hyer,Brenda Pratt,Sarah Chittenden,Glenn D. Flux,Clive L. Harmer,Yong Du,Matthew Gray

doi:10.1097/mnm.0000000000000826

Abstract

ObjectiveThe aim of this retrospective study was to assess the long-term outcome of a personalized dosimetry approach in Graves’ disease aiming to render patients euthyroid from a planned thyroid absorbed dose of 60 Gy.Patients and methodsA total of 284 patients with Graves’ disease were followed prospectively following administration of radioiodine calculated to deliver an absorbed dose of 60 Gy. Patients with cardiac disease were excluded. Outcomes were analysed at yearly intervals for up to 10 years with a median follow-up of 37.5 months.ResultsA single radioiodine administration was sufficient to render a patient either euthyroid or hypothyroid in 175 (62%) patients, the remainder requiring further radioiodine. The median radioactivity required to deliver 60 Gy was 77 MBq. Less than 2% patients required 400–600 MBq, the standard activity administered in many centres. In the cohort receiving a single administration, 38, 32 and 26% were euthyroid on no specific thyroid medication at 3, 5 and 10 years, respectively. Larger thyroid volumes were associated with the need for further therapy. The presence of nodules on ultrasonography did not adversely affect treatment outcome.ConclusionA personalized dosimetric approach delayed the long-term onset of hypothyroidism in 26% of patients. This was achieved using much lower administered activities than currently recommended. Future studies will aim to identify those patients who would benefit most from this approach.

Highlights

The optimal radioiodine treatment strategy for Graves’ disease is controversial as reflected in the differing guidance offered by international guidelines
In the cohort receiving a single administration, 38, 32 and 26% were euthyroid on no specific thyroid medication at 3, 5 and 10 years, respectively
Larger thyroid volumes were associated with the need for further therapy

Summary

Introduction

The optimal radioiodine treatment strategy for Graves’ disease is controversial as reflected in the differing guidance offered by international guidelines. The American Thyroid Association aims to render patients hypothyroid by administering 370–555 MBq (10–15 mCi) or 5.5 MBq (150 mCi) per gram of thyroid tissue [1]. The Royal College of Physicians (UK) recommends a fixed activity of 400–600 MBq for rapid elimination of hyperthyroidism accepting that a significant proportion of patients will require life-long L-thyroxine with this approach [2]. The European Association of Nuclear Medicine recommends administration of an activity of radioiodine calculated to give an absorbed dose of 150 Gy to the thyroid where the aim is to restore euthyroidism [3]. An individualized approach on the basis of dosimetry aims to administer the minimum activity of

Methods

Results

Conclusion