Endocrine Abstracts

Background: Differentiated thyroid carcinoma is the most common endocrinological malignancy with an increasing incidence over the last 30 years. It is the fifth most common cancer among the young population (15–39 years), with women being more frequently affected. Surgical removal of the tumour is the standard treatment method. In indicated cases, total thyroidectomy with subsequent adjuvant radioiodine administration is performed, despite international trends towards less aggressive treatment. International studies have reported anti-Müllerian hormone (AMH) as the best endocrine marker to assess physiological age-related oocyte loss for healthy women. The possible adverse effects of radioiodine (RAI) on ovarian function and female fertility for women are currently being investigated.

Methods: The aim of our ongoing prospective study is to determine serum AMH to estimate ovarian reserve for premenopausal women treated with RAI. Over the course of one year, 33 serum samples from women with thyroid cancer and 3 serum samples from healthy women were examined. The mean age of the whole group was 35.5 years. The mean RAI dose was 4 888 MBq. AMH levels were compared before and after radioiodine treatment (4–6 months after RAI, 8–12 months after RAI). The Enzyme-Linked ImmunoSorbent Assay (ELISA) microtiter plates were used to test blood samples.

Results: Mean of the AMH level was 5.4 ng/mL (n= 33) prior to RAI. A significant decrease in AMH levels occurred 4–6 months after therapy (mean 1.8 ng/mL) and 22.2 % of patients experienced a decrease in AMH levels to 0 ng/mL from non-zero levels after treatment. A subsequent slight rise in AMH level was 8–12 months after RAI (mean 2.7 ng/mL). Equivalent radioiodine dose to the ovaries was calculated with a mean of 180 mGy in the treated group. Very low AMH values at the beginning of treatment and after radioiodine administration were significant in women aged around 50 years.

Conclusion: AMH has gained interest as a possible predictor of ovarian reserve in recent years. The effects of RAI on the change in AMH levels were more significantly observed in patients older than 35 years. Although findings from retrospective studies suggest a slight decrease in AMH levels after radioiodine treatment of DTC, a long-term decrease in pregnancy rates has not been demonstrated. However, more data from prospective studies are needed.