Determinants of longterm outcome of radioiodine therapy of sporadic non‐toxic goitre

Abstract

The size of sporadic nontoxic goitres is reduced on average by 50% after a single dose of 4.77 MBq 131I/g thyroid. Independent determinants of the relative decrease in thyroid volume are administered 131I dose and initial goitre size. Nonresponders (14%) and those with late recurrence of goitre growth (8%) have larger goitres and more often dominant nodules than responders. Determinants of postradioiodine hypothyroidism (cumulative risk 58% after 8 years) are the presence of TPO antibodies, a family history of thyroid disease and a relatively small goitre. The implications of these findings are that the efficacy of a given 131I dose can be enhanced when administered at an earlier stage when the goitre is still smaller, albeit at the expense of an increased risk for developing hypothyroidism.

Controversies in radioiodine therapy: relation to ophthalmopathy, the possible radioprotective effect of antithyroid drugs, and use in large goitres

“…In moderately enlarged, non-toxic multinodular goitres, the effect of 131 I therapy on goitre reduction seems to correlate inversely with the initial size (82). Theoretically, such a relationship is plausible, because a larger fraction of the gland degenerates in the voluminous multinodular goitre.…”

“…If high-dose 131 I is administered in divided doses, admission of the patient to hospitalrequired by official regulations -can be avoided. In the case of smaller goitres, a second 131 I dose causes a further reduction of the goitre (82). In patients with large goitres, Howarth et al (83) have shown that four doses, each of 555 MBq (15 mCi), given 1 month apart, resulted in a goitre reduction in 92% of patients.…”

The effects of recombinant human thyrotropin, in normal subjects and patients with goitre

“…However, there is no consensus regarding the most favourable treatment (Bonnema et al ., 2000(Bonnema et al ., , 2002b. In some countries, including ours, 131 I has been used for decades in the treatment of symptomatic nontoxic nodular goitre, resulting in a mean thyroid volume reduction ranging from 40% to 60% within 1-2 years after treatment (Hegedüs et al ., 1988;Nygaard et al ., 1993;Le Moli et al ., 1999) as described comprehensibly by Hegedüs et al . (2003).…”

Radioiodine therapy in non-toxic multinodular goitre. The possibility of effect-amplification with recombinant human TSH (rhTSH)

“…Also, patients with very large and/or substernal goitres have been treated with beneficial results [35,36,40]. Although normalization of the thyroid volume is only rarely achieved by 131 I therapy of multinodular goitre, symptoms are in most cases improved considerably and patient satisfaction is high [4,36,37]. If a secondary increase in thyroid volume is seen, this should raise suspicion of malignancy.…”