Endocrine Abstracts

Introduction: The treatment of hyperthyroidism is complex. Radio-iodine administration remains the definitive option despite debate regarding optimum dosage and strategy.

Method: Thyroid status in all patients receiving first dose radio-iodine over a 5 year period was reviewed at 3, 6, 12 and (most at) 24 months. Radio-iodine doses were individualised depending on thyroid gland size, co-morbidities and patient choice. The objective was euthyroidism with hypothyroidism an acceptable outcome.

Results: There were 215 patients aged 16 to 85. Radio-iodine dosage ranged from 250 to 531 MBq (average 359 MBq). Six and 12 month post-radio-iodine thyroid status is reported below.

Discussion: Hypothyroidism and euthyroidism are acceptable outcomes from radio-iodine therapy. This was achieved in 88% of patients comparing favourably with previously reported data. In addition the percentage achieving this outcome at 6, 12 and 24 months was not significantly different indicating that reliable predictions of thyroid status can be made at 6 months.

Twenty-seven patients remained toxic at 12 months This appears to be independent of the dose of radio-iodine administered (average dose 353 MBq), indicating that higher doses did not improve treatment objectives. All 27 patients were toxic at 6 months and one of the interesting characteristics amongst others in this ‘treatment failure’ group was a greater percentage of males 41 vs 29% overall. All but 2 ‘treatment failure’ patients had Graves’ disease.

The findings have interesting implications for the planning of radio-iodine administration.