Even basic ultrasonographic characteristics (shape, echogenicity and echogenic hilum, calcifications, and intranodal cystic necrosis) help in the differentiation between metastatic and nonmetastatic lymph nodes in patients with papillary thyroid carcinoma.

Our aim was to assess testicular function in patients treated with high-dose radioiodine. Luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone levels were determined in 52 men with thyroid carcinoma before and 6, 12, and 18 months after radioiodine therapy (3.7-5.5 GBq 131 I; mean, 4.25 GBq 131 I) (group 1) and were also determined before and 18 months after the last radioiodine therapy in 22 patients who received high cumulative activities (13-27.7 GBq; mean, 20.3 GBq 131 I) (group 2). FSH levels were increased 6 months after therapy in all patients of group 1, while a decline was observed after 12 months, with 37 of 52 (71%) subjects presenting normal values. FSH values returned to normal after 18 months in all patients. In group 2, 12 of 22 (54.5%) patients presented elevated FSH and 8 (66%) of these individuals had oligospermia. Six months after radioiodine, increased LH levels were observed in only 5 of 52 (9.6%) patients of group 1, which returned to normal after 12 months, and in 5 of 22 (22%) of group 2. All patients showed normal testosterone levels. We conclude that 131 I therapy may cause impairment of testicular function. A generally transient increase in FSH is highly common but is usually reversed within 18 months. Oligospermia was common (one third) after high cumulative 131 I activities. Becausee we did not perform a spermiogram before therapy, we cannot state that high cumulative 131 I activities cause permanent infertility. We recommend the routine use of sperm banks in the cases of men who still wish to have children and who will undergo therapy with 131 I activities of 14 GBq or more or in the case of patients with pelvic metastases. 667

This study demonstrated the efficacy of low doses in patients with lower remnants after surgery (uptake <2%), the inverse correlation between uptake and ablation efficacy with low and high doses, and the usefulness of the measurement of cervical uptake for the definition of the ablative 131I dose.

Posttherapy scanning provides important information, even in patients whose pretherapy WBS is positive for metastases, with this approach being useful both during the first ablation and subsequent treatment.

Radioiodine causes transitory alterations in ovarian function even in younger women and after a mean activity of 4.2 GBq (115 mCi).