Long-term radioiodine treatment effective in toxic multinodular goiter

Treatment with 15 mCi of radioiodine (RAI) leads to low hypothyroidism rates in adult patients with toxic multinodular goiter (TMNG), with high cure rates and significant volume reduction, according to a study. This effect persists in the long term.

A total of 153 RAI-naïve patients with TMNG were included in this population-based, retrospective analysis conducted in Siena, Italy, with up to 12 years of follow-up. The investigators assessed thyroid functions, antithyroid antibodies, and ultrasound scans before and yearly after RAI. The following outcomes were measured: hyperthyroidism cure, hypothyroidism, volume reduction, nadir and regain, and antibody titre change.

Mean volume reductions ≥50 percent were observed at 3 years after RAI, with the greatest annual reduction seen during the first year (30±17.8 percent; p<0.001). Majority of the patients (60 percent) achieved their volume nadir 3 to 6 years after RAI. Twenty-two patients had volume regain, but the net reduction was statistically significant as late as 9 years post-RAI (p=0.005).

Mean time to hypothyroidism onset was 2.7±2.4 years and correlated with greater decrease in volume (p=0.01). The number of hyperthyroid patients decreased by nearly 50 percent per year without additional RAI during the first 3 years post-treatment. No statistically significant association was observed between antibody titres and thyroid functions, except for antithyrotropin receptor antibodies and hyperthyroidism (p=0.004).

Of the patients, 61.6 percent were euthyroid, 11 percent hyperthyroid (4.8 percent over), and 27.4 percent hypothyroid (2.7 percent overt) at the end of follow-up. Hyperthyroidism was cured in 89 percent of patients.