Tehran University Medical Journal (Jun 2004)
Effects Of Treatment With Radioactive Iodine On Gonadal Functions In Patients With Differentiated Thyroid Cancer
Abstract
Background: The purpose of this study was to evaluate the effect of treatment with radioactive iodine on the function of gonads in males and females with follicular and papillary thyroid carcinoma. Materials and Methods: Consenting patients in the reproductive age were grouped according to the cumulative dose of received radioiodine and followed for at least 12 months. For all men, serum levels of FSH, LH, and testosterone were measured; some (53 cases) were also studied by semen analysis. For women, tests for serum levels of LH, FSH, estrogen, and progesterone were performed. Results: Overall, 246 patients (159 females, 87 males) were studied. In 87.4% of men, there was an increase in serum FSH level after radioiodine therapy, in 20.7% of whom the level remained high during follow-up period. The average serum level of FSH after each course of treatment was significantly higher than the level before treatment (p<0.01), and there was a meaningful correlation with the cumulative dose of received iodine (p<0.001). Reduced number of sperms was shown in 35.8% of male patients, among whom 73.7% also showed reduced motility. In 36.8% of the patients with reduced sperm number (13.2% of the total), this finding was persistent during the follow-up period. Increased level of FSH was correlated with reduced sperm counts in all doses (p<o.oo5). There was no significant correlation between serum levels of LH and testosterone with iodine treatment in males (p=0.47). In women, no significant correlation between gonadal-hypophyseal hormones and treatment with radioactive iodine was found, and there were no signs and symptoms of sexual dysfunction. Infertility was not noticed in any patient and no case of abortion was found. Conclusion: It seems that cells in spermatogonia lineage (in contrast to Leydig cells) are radiosensitive, with the sensitivity related to the cumulative dose of received radioactive iodine. But in the oogonia cell line, the radiosensitivity is insignificant.
