Failure of Radioactive Iodine in the Treatment of Hyperthyroidism

Abstract

Introduction Persistent or recurrent hyperthyroidism after treatment with radioactive iodine (RAI) is common, and many patients require either additional doses or surgery before they are cured. The purpose of this study was to identify patterns and predictors of failure of RAI in patients with hyperthyroidism. Methods We conducted a retrospective review of patients treated with RAI from 2007–2010. Failure of RAI was defined as receipt of additional dose(s) and/or total thyroidectomy. Using a Cox proportional hazards model, we conducted univariate analysis to identify factors associated with failure of RAI. A final multivariate model was then constructed with significant (p < 0.05) variables from the univariate analysis. Results Of the 325 patients analyzed, 74 patients (22.8%) failed initial RAI treatment. 53 (71.6%) received additional RAI, 13 (17.6%) received additional RAI followed by surgery, and the remaining 8 (10.8%) were cured after thyroidectomy. The percentage of patients who failed decreased in a step-wise fashion as RAI dose increased. Similarly, the incidence of failure increased as the presenting T3 level increased. Sensitivity analysis revealed that RAI doses < 12.5 mCi were associated with failure while initial T3 and free T4 levels of at least 4.5 pg/mL and 2.3 ng/dL, respectively, were associated with failure. In the final multivariate analysis, higher T4 (HR 1.13, 95% CI 1.02–1.26, p=0.02) and methimazole treatment (HR 2.55, 95% CI 1.22–5.33, p=0.01) were associated with failure. Conclusions Laboratory values at presentation can predict which patients with hyperthyroidism are at risk for failing RAI treatment. Higher doses of RAI or surgical referral may prevent the need for repeat RAI in selected patients.

Comparative analysis of radioactive iodine versus thyroidectomy for definitive treatment of Graves disease

“…Those managed by total thyroidectomy tended to have more transient complications but with greater remission rates. The remission rate for adults was comparable to a recent study by Schneider et al 2 and other studies. 21–23 Of those failing initial RAI who opted for operative treatment, all were successfully treated.…”

“…1,2,8–10 However, recent guidelines have considered thyroidectomy as a comparable treatment option to RAI with an equivalent, long-term quality of life. 2,8,11 In addition, recent publications show that the trend in definitive treatment of GD has become primarily operative in some US institutions serving patients with low socioeconomic status. 3,12,13 …”

“…Contraindications to RAI are pregnancy, lactation, and presence of thyroid cancer. 2,8 In the United States, operation is recommended in those with symptomatic compression, large goiters (>80 g), concern for malignancy, the presence of a large nonfunctioning or hypofunctioning nodule, hyperparathyroidism, women desiring pregnancy within 4–6 months, and moderate to severe, active GO. 8 …”

Thyroidectomy for Graves' disease in children: Indications and complications

“…In their historic cohort, similar to our findings in a more contemporary group, failure of medical therapy was the indication for surgery in 60%, and side effects of ATD was the indication in another 10% of patients. Three patients in their series (4%) failed RAI treatment prior to surgery, and while this was a fairly frequent indication in our adult population [23], no children in our series had failed RAI as the indication for their surgery.…”

Clinical and Socioeconomic Factors Influence Treatment Decisions in Graves’ Disease

“…(8) Other indications include failure or refusal of RAI therapy or complications associated with anti-thyroid medications. (9) One previous study reported a disproportionate number of patients with lower socioeconomic status (SES) undergoing surgery(10), and raised the possibility that social or economic factors such as insurance status, income, race, or education could also be influencing choice of treatment.…”