Despite extended exposure to high doses of estrogen therapy, levels of prolactin did not rise in transgender patients.
Joshua Safer, MD
A new study conducted by researchers at Mount Sinai Health System found that in a retrospective chart review of nearly 100 transgender (male to female) patients receiving feminizing hormone therapy, levels of prolactin did not rise—alleviating concern about the possibility of developing autonomous prolactinomas later in life.
This is the first study to measure prolactin levels in transgender patients receiving the standard feminizing hormone therapy regimen that’s used in the US. The study demonstrates that gender-affirming treatment for transgender individuals may be safer than initially thought.
Current medical guidelines recommend physicians to routinely check prolactin levels in patients receiving hormone therapy, and although overproduction of prolactin isn’t life-threatening, it can impair vision and produce other side effects.
“Our data suggests that there may be no significant rise in prolactin when transgender women are treated with estrogen and that it may be unnecessary to monitor prolactin in patients receiving this treatment,” lead author, Joshua Safer, MD, executive director, center for transgender medicine and surgery, Mount Sinai, said in a statement.
Study researchers assessed the impact of estrogen therapy with adjunctive spironolactone on prolactin levels by examining levels of estrogen, testosterone, prolactin and spironolactone from 98 transgender women treated with estrogen therapy at the Endocrinology Clinic at Boston Medical Center. For several patients, up to 6 years of data were available.
Patients ranged in age from 20—68 years old, with a mean age of 41 years. The average body mass index (BMI) of patients in the sample ranged from 19–44, with a mean of 28.
The standard transfeminine hormone treatment approach at Boston Medical Center includes either daily oral estradiol or conjugated estrogens, along with adjunctive spironolactone. The average dose of spironolactone given was 161 mg, while the average dose of estradiol given was 3.1 mg.
In the study, 78.5% of patients were on oral estradiol, 18.75% were on conjugated equine estrogens and 2.5% received transdermal estradiol.
Despite extended exposure to high doses of estrogens and testosterone-lowering medications, there were no elevated levels of prolactin reported over a 6-year period (p > 0.05). Additionally, there was no correlation observed between BMI and prolactin levels among patients (p > 0.05).
Researchers noted that while the study was limited by sample size, among the 98 patients there were no prolactinomas diagnosed despite surveillance. Moreover, there was no rise in serum prolactin that could be associated with exogenous estrogen treatment.
Data suggest that previous reports of elevated levels among medically treated transgender women may reflect as an over-sampling bias or of the impact of cyproterone acetate others reported, compared to estrogens.
Findings concluded that no estrogen dose was associated with prolactin level rise in a cohort of transgender women treated over multiple years with the standard US transfeminine medical regimen of estradiol and adjunctive spironolactone. It’s suggested that physiologic-level estrogen therapy does not induce prolactinomas or hyperprolactinemia.
Since researchers proposed that there is no significant rise when treated with spironolactone as the adjunct anti-androgen, it’s not necessary to monitor those on this treatment combination.