Endocrinological and ovarian histological investigations in assigned female at birth transgender people undergoing testosterone therapy

Research question: What are the hormonal and ovarian histological effects of a gender affirming hormonal therapy in assigned female at birth (AFAB) transgender people? Design: Prospective observational study of 70 AFAB transgender people taking testosterone therapy before gender-affirming surgery (hystero-oophorectomy). A gynaecological ultrasonographic scan was undertaken and serum hormone concentrations measured, including anti-Mullerian hormone (AMH) and androgenic profile. Histological ovarian evaluation was assessed in both ovaries, including the developmental stages of the follicles. Results: The mean age of the population was 277+/-5.14 years. The main biochemical parameters were total testosterone levels 781.5 +/- 325.9 ng/dl; AMH levels 3.2 +/- 1.4 ng/ml; FSH and LH levels 4.9 +/- 2.5 IU/l and 3.9 +/- 2.9 IU/l, respectively; and oestradiol values 476 +/- 13.7 pg/ml. Fifty-five AFAB underwent gynaecological ultrasound before surgery and antral follicles were found in 43 out of 47 ultrasounds (91.5%) (without the presence of a dominant follicle or corpus luteum). Histological follicles were mostly in the primordial stage (88.0) and 3.3% were atretic. The thickness of the tunica albuginea was widely heterogeneous (range 0.15-1.45 mm) and luteinization of the stromal cells was observed in 68.6% of the samples. A negative correlation between testosterone levels and total antral follicles was found (R-s = -0.306, P = 0.029). Conclusions: AFAB transgender people taking testosterone therapy show cortical follicle distribution in the range previously reported in fertile cisgender women of reproductive age. The follicular population may not be altered as a result of the gender-affirming hormonal therapy, although some cortical and stromal changes have been observed.