Low estrogen doses normalize testosterone and estradiol levels to the female range in transgender women

Abstract

OBJECTIVE:The ideal dosage of cross-sex hormones remains unknown. The aim of this study was to evaluate the luteinizing hormone, follicle-stimulating hormone, testosterone, estradiol and prolactin levels after low-dose estrogen therapy with or without cyproterone acetate in transgender women.METHODS:The serum hormone and biochemical profiles of 51 transgender women were evaluated before gonadectomy. Hormone therapy consisted of conjugated equine estrogen alone or combined with cyproterone acetate. The daily dose of conjugated equine estrogen was 0.625 mg in 41 subjects and 1.25 mg in 10 subjects, and the daily dose of cyproterone acetate was 50 mg in 42 subjects and 100 mg in one subject.RESULTS:Estrogen-only therapy reduced the testosterone, luteinizing hormone and follicle-stimulating hormone levels from 731.5 to 18 ng/dL, 6.3 to 1.1 U/L and 9.6 to 1.5 U/L, respectively. Estrogen plus cyproterone acetate reduced the testosterone, luteinizing hormone and follicle-stimulating hormone levels from 750 to 21 ng/dL, 6.8 to 0.6 U/L and 10 to 1.0 U/L, respectively. The serum levels of luteinizing hormone, follicle-stimulating hormone, testosterone, estradiol and prolactin in the patients treated with estrogen alone and estrogen plus cyproterone acetate were not significantly different. The group receiving estrogen plus cyproterone acetate had significantly higher levels of gamma-glutamyltransferase than the group receiving estrogen alone. No significant differences in the other biochemical parameters were evident between the patients receiving estrogen alone and estrogen plus cyproterone acetate.CONCLUSION:In our sample of transgender women, lower estrogen doses than those usually prescribed for these subjects were able to adjust the testosterone and estradiol levels to the physiological female range, thus avoiding high estrogen doses and their multiple associated side effects.

A systematic review of antiandrogens and feminization in transgender women

“…This showed a significantly lower median serum total testosterone concentration in those treated with CPA (0.8 nmol/L), compared to spironolactone (2.0 nmol/L) and estradiol alone (10.5 nmol/L) ( P = .005 after adjustment for serum estradiol concentration, estradiol dose, spironolactone dose, CPA dose and age). In contrast, Cunha et al 20 observed a significant reduction in serum total testosterone concentrations at 6 months compared to baseline in a retrospective analysis of 51 transgender women treated with conjugated equine oestrogens (CEE) alone or with CPA 50‐100 mg daily, but no significant between‐group difference (median serum total testosterone concentration at 6 months 21 ng/dL (0.73 nmol/L) in the CPA group versus 18.0 ng/dL (0.62 nmol/L) in the CEE alone group, P = .217).…”

Health considerations for transgender women and remaining unknowns: a narrative review

“…Oestrogens and anti-androgens suppress serum testosterone levels and block androgen action, and it is expected that testosterone levels will decline on all forms of treatment. 26,27 Transdermal oestradiol patches or gel (and depending on availability, parenteral oestradiol injections) may be safer with regard to triglycerides and clotting risk than oral oestradiol by bypassing first-pass hepatic metabolism. 28 Transdermal oestradiol use has been proposed and implemented particularly in older TW (e.g.…”

Midwifery Care for Transfeminine Individuals

“…Although there is no clear consensus, most experts agree that a physiologic estradiol range for transfeminine individuals desiring binary gender affirmation is approximately 200 pg/mL, with a commonly cited range from 80 to 250 pg/mL based on expert opinion . Agreement on physiologic testosterone level is more forthright, with a commonly cited goal of less than 55 ng/dL for binary gender affirmation .…”