Nonsurgical Approaches to the Management of Thyroid Nodules

Sebastiano Filetti; Cosimo Durante; Massimo Torlontano

Disclosures

Nat Clin Pract Endocrinol Metab. 2006;2(7):384-394. 

In This Article

Radioiodine Treatment

Radioactive [131]I (RAI) has been used for over 50 years to treat clinical or subclinical hyperthyroidism due to Graves' disease or autonomously functioning thyroid nodules (either toxic or nontoxic).[53] This treatment exploits the increased iodine uptake of hyperfunctioning thyroid cells. The effectiveness of RAI in reducing the size of the thyroid gland is widely recognized[54,55] and, for this reason, it has also been used for the treatment of nonautonomous thyroid nodules.[56] At the doses commonly used (5–30 mCi, 185–1,110 MBq), RAI seems to be devoid of major side effects. It is contraindicated in pregnant or breast-feeding women.

Most solitary, toxic thyroid nodules can be cured with a single dose of RAI. In a long-term study of 62 patients with autonomously functioning toxic nodules who had received RAI (minimum follow-up 12 months), only 9 required a second, calculated dose.[54] By 3 months after treatment, 75% of the treated patients had no toxic symptoms, and thyroid volumes had decreased by a mean of 35%. At the 5-year follow-up, fewer than 10% of the patients presented with hypothyroidism.[54] The efficacy and safety of treatment were optimal when the RAI dose ranged from 1.0 to 1.5 mCi/cm2 (37.0 to 55.5 Mbq/cm2) of the nodule area, as measured on the scintiscan.[57]

There have been a number of prospective and retrospective studies of RAI treatment for toxic, multinodular goiter. Calculated and fixed doses (e.g. 7–10 mCi, 259–370 MBq) have been tested.[55,58,59] In a prospective study of 130 patients, a cure rate of 92% was reported after administration of one or two calculated doses (median dose 370 MBq), and about half of the cured patients were euthyroid 3 months after treatment.[55]

Significant shrinkage (ranging from 31% to 60%) can be also achieved in patients with nontoxic multinodular goiter.[56] Mild pain was reported in roughly 3% of treated patients, which was probably caused by transient radiation thyroiditis.[60] Transient thyrotoxicosis and, rarely, development of anti-TSH-receptor antibodies and consequent Graves' disease, can occur.[61] About 20–30% of patients developed hypothyroidism 3–5 years after RAI; the presence of pre-existing antibodies against thyroid peroxidase can predispose to post-RAI hypothyroidism.[56,60,61]

Uptake of RAI may be reduced in patients with multinodular goiters, especially the nontoxic forms, and increased RAI doses should be given in these cases. Recent reports (published in 2003 and 2005) indicate that pretreatment with a low dose (0.3 mg) of recombinant human TSH can enhance RAI uptake, and allow effective treatment with low doses of RAI.[62,63,64] In a randomized, double-blind study, this approach produced a 74% increase in the dose absorbed by the thyroid.[63] Additional, controlled studies are needed to determine whether this effect is accompanied by significantly greater reductions in goiter volumes compared with standard RAI treatment. A sudden rise of thyroid hormones after stimulation with recombinant human TSH could be potentially unsafe in elderly and cardiopathic patients; however, no serious side effects have been reported.[65]

For large, multinodular goiters that exert pressure on surrounding structures and/or are cosmetically unacceptable, surgery is the treatment of choice. RAI is an effective alternative for elderly patients, those with high surgical risks (e.g. cardiopathic patients), or when surgery is refused.[55,56,57,58,59,60,61,62,63,64]

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