Low-Dose Cyproterone Acetate Treatment for Transgender Women

Background Transgender women with intact gonads receive lifelong hormonal treatment to suppress physiologic androgen production, the optimal efficacious and safe cyproterone acetate (CPA) dose has not been established. Aim To assess the effectiveness and safety of low-dose (10–20 mg/day) compared with high-dose (50–100 mg/day) CPA treatment. Methods We conducted a historical cohort study of transgender women treated at a tertiary center for transgender health. Outcome Measures Serum levels of testosterone, estradiol, prolactin, gonadotrophins, liver enzymes, and lipids. RESULTS There were 38 transgender women in the low-dose group and 26 in the high-dose group. Age (median 24.9 years, interquartile range [IQR] 21–30 vs 25 years, IQR 19–35) and follow-up time (median 12 months, IQR 6–23 vs 15 months, IQR 12–36) were similar in the low- and high-dose groups, respectively. Serum gonadotropins and testosterone were suppressed to a similar level at all time points in both groups. Prolactin levels increased significantly in both groups, however, with a more substantial increase in the high- vs the low-dose group (804 ± 121 vs 398 ± 69 mIU/ml at 12 months, respectively, P = .004). Total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglyceride levels were not significantly affected by the dose. Clinical Implications We suggest an adjustment of current clinical practice guidelines to recommend lower doses of CPA for the treatment of transgender women. Strengths & Limitations This is the first demonstration that low-dose CPA treatment of transgender women is effective. Limitations include a relatively small sample and retrospective study design. CONCLUSION Low-dose CPA treatment of transgender women is as effective as high-dose treatment and possibly safer.