Radioactive iodine treatment may reduce ovarian reserve

BOSTON — Premenopausal women who underwent radioactive iodine therapy for differentiated thyroid cancer saw a sustained decline in anti-Mullerian hormone levels in the first year following treatment, indicating decreased ovarian reserve, according to study data presented here.

“We have been able to show for the first time, in a prospective fashion, that high-dose radioactive iodine treatment administered to normally menstruating women with differentiated thyroid cancer causes an irreversible damage to their ovarian reserve, as assessed by measurement of anti-Mullerian hormone,” Karen Tordjman, MD, associate professor of medicine at the Sackler Faculty of Medicine at Tel Aviv University, told Endocrine Today.

Karen Tordjman

In an ongoing study, Tordjman and colleagues analyzed data from 30 premenopausal women undergoing radioactive iodine treatment following surgery for differentiated thyroid cancer. All women reported regular menses prior to treatment; 19 had borne children. Researchers assessed anti-Mullerian hormone (AMH) via immunoassay at baseline and every 3 months for up to 1 year following radioactive iodine therapy. Baseline AMH levels were inversely correlated with age (r = 0.49; P = .006).

To date, 23 participants, all diagnosed with stage 1 differentiated thyroid cancer, received radioactive iodine therapy at a mean dose of 110.7 mCi; 18 were reevaluated after treatment. In the 3 months following treatment, AMH levels fell from a mean baseline of 3.43 ng/mL to 1.9 ng/mL (P = .001). AMH levels remained below baseline at 6, 9 and 12 months (2.4 ng/mL, 2.6 ng/mL and 2.8 ng/mL, respectively).

To determine whether there was a dose effect, researchers grouped four participants who received an ablative dose of 30 mCi with five women treated with radioactive iodine therapy for Graves’ disease in dosing ranges from 10 to 22 mCi; baseline AMH levels for these women were 2.5 ng/mL and did not change following treatment.

The researchers noted that the findings add further weight to current precautions advocated for low-risk thyroid cancer patients considering radioactive iodine therapy.

“We therefore believe that our data are an additional piece of evidence that RAI treatment is not inconsequential with respect to reproductive potential in women, and this fact should be taken seriously into consideration when planning RAI therapy, particularly in young, low-risk women,” Tordjman told Endocrine Today. “We also believe the baseline level of AMH could be keyed in the decision process when considering RAI therapy. Additionally, in older women or in women with low baseline levels of AMH who wish to conceive, pretreatment oocyte preservation could be considered.”

Tordjman added that the proof-of-concept, pilot study was not intended to provide data about the actual chances of conceiving after treatment.

“We think properly planned prospective studies of such women, using AMH as one of the parameters, might help us identify the population of women whose reproductive chances are most threatened by this RAI, and those who might benefit most either from not receiving it at all, or at least from taking all appropriate measures for fertility preservation prior to treatment.,” Tordjman said. – by Regina Schaffer

Reference :

Tordjman KM, et al. OR22-6. Presented at: The Endocrine Society Annual Meeting; April 1-4, 2016; Boston.

Disclosure: Tordjman reports no relevant financial disclosures.