Reduction in thyroid volume after radioiodine therapy of Graves' hyperthyroidism: results of a prospective, randomized, multicentre study

Abstract

The reduction in thyroid size in 92 patients treated with radioiodine for Graves' thyrotoxicosis was monitored by ultrasound volumetry. The patients were randomly treated with either a standard 131I activity of 555 MBq or an activity calculated to deliver a thyroid dose of 100 Gy. Within 1 year after radioiodine treatment, a remarkable volume reduction of about 71% (median) (quantile 25% (Q 25) = 49%, Q 75 = 82%, n = 67) was observed. The bulk of this reduction (median 57%, Q 25 = 21%, Q 75 = 74%, n = 92) was found within the first 6 months. Statistical analysis reveals that the effect was clearly related to the thyroid dose actually achieved during therapy. The median reduction obtained 6 months after radioiodine application was 45% for < 100 Gy, 56% for 100-200 Gy and 67% for > 200 Gy (n = 28, 39, 25 respectively). Twelve months after radioiodine application, the effect became less evident: 53%, 68% and 75% respectively (n = 17, 29, 21). The higher median thyroid dose actually achieved by standard than by calculated activity (215 Gy vs. 116 Gy) explains the more pronounced volume reduction in the standard group than in the calculated group; 60% vs. 47% 6 months (n = 47, 45) after radioiodine treatments and 74% vs. 66% 12 months (n = 31,36) after radioiodine application. The relative reduction in thyroid size was just as marked in patients with large thyroids as in those with small glands. The goitre prevalence (thyroid volume > 20 mL in women and > 25 mL in men) was reduced from 73% to only 16% 1 year after radioiodine treatment. In patients with a thyroid volume of more than 60 mL, the median pretherapeutic thyroid volume of 102 mL was reduced to 29 mL. In conclusion, radioiodine treatment in Graves' hyperthyroidism sufficiently reduces thyroid volume in a dose-dependent manner. The findings of this study demonstrate that radioiodine is also an attractive mode of therapy for Graves' patients with substantial thyroid enlargement.

Pediatric Graves’ Disease: Controversies in Management

“…Surgery is preferred in young children (<5 years) when definitive therapy is required and can be performed by an experienced thyroid surgeon. In individuals with large thyroid glands (>80 g), the response to 131 I may be poor [39,59] and surgery is recommended for these patients.…”

Surgical management of pediatric Graves’ disease: an effective definitive treatment

“…Clear indications for thyroidectomy include large glands ([80 g) due to a poor response to RAI [12,13], obstructive or compressive symptoms, requirement for immediate control of the disease, and age younger than 5 years. Even if the worsening of Graves' ophthalmopathy (that may be prevented by coadministering a short course of corticosteroids [14]) has been reported in a small percentage of adults treated with RAI [15], there is no evidence of such complication in children and adolescents undergoing RAI [16].…”

Should radioiodine be the first-line treatment for paediatric Graves’ disease?

“…Surgery may be the optimal definitive treatment in certain patient groups including children under 5 years of age and children with a large goitre ( > 80 g) at diagnosis (34)(35)(36). Complication rates can vary from 15% when performed by paediatric surgeons compared to 4% (p < 0.01) for experienced thyroid surgeons ( > 30 thyroidectomies per year) (37).…”