ESTROGEN LEVELS DO NOT RISE WITH TESTOSTERONE TREATMENT FOR TRANSGENDER MEN.

OBJECTIVE: Existing transgender treatment guidelines suggest that for transmasculine treatment, there is a possible need for estrogen-lowering strategies adjunct to testosterone therapy. Further, guidelines advocate consideration of prophylactic female reproductive tissue surgeries for transgender men to avoid the possibility of estrogen-related health risks. Despite the paucity of objective data, some transgender men seek conversion inhibitors. We sought to determine estradiol levels in transgender men treated with testosterone therapy and the change in those levels with treatment, if any.
METHODS: Estradiol levels were extracted from the electronic medical records of 34 anonymized transgender men treated with testosterone therapy at the Endocrinology Clinic at Boston Medical Center. Data were sufficient to observe 6 years of follow-up.
RESULTS: With increased testosterone levels in trans-gender men, a significant decrease in estradiol levels was noted. There was a significant negative correlation between testosterone levels and body mass index, which may serve to explain part of the mechanism for the fall in estradiol levels. Even though the fall in estradiol levels was significant statistically, the actual levels remained within the normal male range, even with 6 years of follow-up.
CONCLUSION: These data suggest that when exogenous testosterone is used to achieve normal serum male testosterone levels for transgender men, it is converted to normal male levels of estradiol, with some decline in those estradiol levels that might be attributable to a fall in fat mass. There appears to be no role for aromatase conversion inhibitors or other estrogen-reducing strategies in trans-gender men. Abbreviation: BMI = body mass index.