Ovarian function after radioiodine therapy in patients with thyroid cancer

Objective: To assess ovarian function in young women treated with radioiodine. Methods: The study was conducted on 50 women with thyroid carcinoma aged less than 40 years (mean, 29.8 years), with regular menstrual cycles and normal FSH levels prior to radioiodine therapy. FSH determination was repeated 6 and 12 months after radioiodine therapy (mean, 4.24 GBq iodine-131) and menstrual cycles were monitored during this period. Results: Twenty percent of the patients reported amenorrhea during the first year. FSH levels increased after 6 months (from 5.1 +/- 1.8 to 10.6 +/- 2.2 IU/1, p < 0.00 001) and 28% of the patients showed elevated values, which had returned to normal by the end of the first year. Conclusion: Radioiodine causes transitory alterations in ovarian function even in younger women and after a mean activity of 4.2 GBq (115 mCi).