Endocrine Abstracts

Introduction: Transgender women and gender diverse individuals with functioning testicles who are eligible for estrogen-based hormone therapy need to use antiandrogens in addition to estrogen to achieve adequate desired physical changes and suppress testosterone to cisgender women levels. Sublingually administered estradiol can achieve higher serum estradiol levels than traditionally administered oral estradiol, but may require multidaily dosing (1). We present a case of transgender woman who uses estrogen sublingually and cyproterone acetate as antiandrogen.

Case: Twenty-four years old transgender woman has been using estradiol in dose of 1 mg four times a day sublingually for 6 months. She has been started on cyproterone acetate 12.5 mg/day as antiandrogen. She has no chronic disease in her past medical history. During her fourth month follow-up visit, the laboratory values as FSH:1.93 U/l, LH: 5.4 U/l, estradiol 131 pg/ml, testosterone <12 ng/dl, prolactin level was 141.2 mg/l. When the prolactin level was measured in other day, it confirmed the high prolactin levels. She has no galactorrhea. There was no gender affirming surgery in her medical history. She has no complaint of headache or visual problems which could accompany with pituitary adenoma. Cyproterone acetate was stopped and after 6 week of period in which sublingual estradiol was the only gender affirming hormonal therapy, prolactin level turned back to normal levels as 15.7 mg/l. She continued to have sublingual estradiol as gender affirming hormonal therapy. Appropriate testosterone suppression was provided with estrogen only therapy.

Conclusion: Hyperprolactinemia can be seen in transgender women receiving gender affirming hormonal therapy. Cyproterone acetate could be a cause for high prolactin levels. Not only cyproterone acetate but also there are cases in the literature that shows prolactin increase with sprinolactone use as antiandrogen. It has been shown that normalization of prolactin levels occurs when cyproterone acetate is ceased. However, antiandrogens is generally needed to provide suppression of testosterone levels in transgender women. In our case, cyproterone acetate caused increase in serum prolactin levels although it has been given in low doses. We would like to draw attention to the fact that sublingual use of estradiol could provide better serum estradiol levels and testosterone suppression compared to oral use of estradiol.

References: Doll E, Gunsolus I, Thorgerson A, Tangpricha V, Lamberton N, Sarvaideo JL. Pharmacokinetics of Sublingual Vs Oral Estradiol in Transgender Women. Endocr Pract. 2022;28(3):237-242.