Influence of iodine-131 dose on the outcome of hyperthyroidism in children.

OBJECTIVES

Iodine-131 is an effective treatment for Graves' hyperthyroidism in children and adults. Yet the responses to treatment as related to iodine-131 dose in children are not well-defined. The objective of this study was to examine the relationship between the dose of iodine-131 in children with hyperthyroidism and thyroid status 1 year after treatment.

METHODS

We examined the outcome of iodine-131 treatment in children and adolescents with Graves' disease, as related to dose. Three iodine-131 doses were compared: 72 to 108 Gy (80-120 microCi/g), 180 to 225 Gy (200-250 microCi/g), and 270 to 364 Gy (300-405 microCi/g) in 31 patients ranging in age from 7 to 18 years old. Thyroid status was assessed >1 year after therapy.

RESULTS

We found that doses of 100 Gy (110 microCi/g), 200 Gy (220 microCi/g), and 300 Gy (330 microCi/g) resulted in hypothyroidism in 50%, 70%, and 95% of treated individuals, respectively. These data show that to insure ablation of thyroid tissue doses, >270 Gy (300 microCi/g) is needed, especially when the thyroid is large.