Endocrine Abstracts

Severe thyroid dysfunction may lead to menstrual disorders and subfertility via direct and indirect interactions with the hypothalamo–pituitary–ovarian axis and the reproductive organs. However, the exact prevalence of subfertility in women with thyroid disorders remains unknown. Fertility problems may persist after restoring normal thyroid function, and then surgery and/or an assisted reproductive technology (ART) may be necessary to obtain a pregnancy. The initial step in an ART treatment is the ovarian stimulation, putting strain on the thyroid gland, potentially leading to (permanent) hypothyroidism in women with thyroid autoimmunity (TAI) or when already treated with thyroid hormones (LT4). Moreover, women with ovarian and unexplained causes of subfertility have a higher prevalence of TAI. In women with TSH levels >4.0 mIU/l, fertilisation rates, embryo quality and live birth rates may be impaired and improved with LT4 therapy. The increased use of intracytoplasmic sperm injection (ICSI) as a type of ART on pregnancy outcomes in women with TAI deserves more attention as therapeutic tool. In euthyroid women with TAI, LT4 should not be given systematically, but on a case-by-case basis if serum TSH is >2.5 mIU/l. Women already treated with LT4, should target a serum TSH level <2.5 mIU/l before ART. For all of the above reasons, women of subfertile couples should be screened systematically for the presence of thyroid disorders, and especially serum TSH and TPOAb. In this symposium, we will present the current state of art, discuss the gaps in the knowledge, and finally, make proposals for future investigations.