Side-effects of iodized oil administration in patients with simple goiter

The objective of this study was to determine side-effects associated with iodized oil injection in patients with simple goiter. In an iodine-deficient population, 3420 patients with simple goiter, who were not taking supplemental iodine, were chosen for this study. They received a single intramuscular injection of 1 ml iodized oil, containing 480 mg iodide. Clinical and laboratory evaluations were performed every 3 months for one year and every 6 months for the next 4 years. The incidence of hypo- and hyperthyroidism was 0.6% each, with equal prevalence in both sexes. Most cases of hypo- and hyperthyroidism were observed during the first 5 months after the injection. Eight cases of hyperthyroidism were asymptomatic. A further 8 patients had overt thyrotoxicosis and required treatment with methimazole for 18 months. Recurrence of hyperthyroidism was observed in one patient. Five hypothyroid patients were diagnosed only by abnormal thyroid function tests, and 4 cases needed no treatment. Others received T4 treatment for a mean of 14.5 months. Among 14 T4-treated patients, recurrence of hypothyroidism occurred in 7 patients after treatment was discontinued. Twenty-nine patients (0.8%) were afflicted with dermatologic complications. The most common dermatologic side-effect was urticarial reaction. In 15 subjects, skin lesions appeared 8 to 14 days after injection. It is concluded that side-effects of iodized oil injection are rare, and in most cases the complications are transient and self-limited. The occurrence of iodine induced hyperthyroidism following iodized oil administration is close to the ratio observed in spontaneous thyrotoxicosis.