Functional results of radioiodine therapy with a 300-GY absorbed dose in Graves' disease

Abstract

The aim of this study was to assess the results of high-dose radioiodine therapy given to 43 patients with recurrent hyperthyroidism due to Graves' disease between 1986 and 1992. We chose an intrathyroidal absorbed dose of 300 Gy and determined the applied activity individually, which ranged from 240 to 3120 MBq with a median of 752 MBq. Hyperthyroidism was eliminated in 86% of cases after 3 months and in 100% after 12 months. No patient required a second radioiodine treatment. The incidence of hypothyroidism was 63% after 3 months and 93% after 18 months. Neither the pretherapeutic thyroid-stimulating immunoglobulin level nor the degree of co-existing endocrine ophthalmopathy was correlated with the time at which hypothyroidism developed. Patients with previous radioiodine therapy developed hypothyroidism earlier than patients with previous thyroid surgery. The results show that ablative radioiodine therapy with a 300-Gy absorbed dose is a very effective treatment of hyperthyroidism in Graves' disease, but it should be restricted to patients with recurrent hyperthyroidism combined with severe co-existing disorders or episodes of unfavourable reactions to antithyroid drugs.

Clinical outcome of radioiodine treatment of hyperthyroidism: a follow‐up study

“…This figure is higher than reported from other studies [17]. A cure rate of 100% has been reported using as high absorbed dose as 300 Gy, but following the ALARA principle this procedure should be restricted to selected patients [18].…”

Graves' disease radioiodine-therapy: Choosing target absorbed doses for therapy planning

“…According to Kobe et al, 6 when using a similar method for dose calculation, overall therapeutic success is greater than 95% when doses of 200 Gy are delivered to the thyroid. Moreover, Reinhardt et al 5 and Willemsen et al, 11 when using T eff , a fixed dose of 300 Gy and Marinelli's formula, also en-countered a similar therapeutic response (92% and 95%, respectively) and (100% and 95%, respectively), although 21% of the patients included in the Willemsen study had already undergone previous radioiodine therapy with 150 Gy. However, as stressed by Sisson, 16 a possible failure rate of 5%-10% at 1-year post-radioiodine therapy should not be neglected.…”

“…Otherwise, reaching a consensus on the optimum dose will remain problematic. For example, according to the widely cited study by Willemsen et al 11 a fixed dose of 300 Gy is required to effectively treat all GD patients. However, the methodology for deriving this dose value was not described.…”

“…To date, no optimum thyroidal absorbed dose for treatment of GD has been identified. Although a large range of doses, from 100 to over 400 Gy, has been indicated to treat thyroid disease, [4][5][6][7][8][9][10] including the often-cited value of 300 Gy, 11 this has not been "validated" for the dosimetry methodology used.…”

A NTCP approach for estimating the outcome in radioiodine treatment of hyperthyroidism

“…However, the model suggests that a standard dose delivering up to 100 Gy to the thyroid is required for treatment success, 47 but it was additionally ar- gued that at higher doses ͑i.e., 300 Gy͒, the certainty of prompt control is expected but the hypothyroidism rate is very difficult to reduce. In fact, Willemsen et al 48 at 300 Gy have reported a treatment success rate of 100% with a hypothyroidism rate of 93% at 12 months, while with a mean dose of 103 Gy in our series, we observed 65% and 32.5% ͑Table II͒, respectively. In an attempt to provide a better separation of cure rates from hypothyroidism rates ͑nonablative optimization͒ efforts need to be directed to refine the calculation of the dose of radioiodine.…”