Medroxyprogesterone acetate tied to minimal side effects, lower testosterone levels in transwomen

Use of the feminizing hormone therapy medroxyprogesterone acetate (MPA) results in minimal side effects, unchanged oestradiol levels and a decline in testosterone in a cohort of transwomen, a study has found.

“MPA is a widely used progestin in feminizing hormone therapy,” the investigators said. “However, the side effects and hormonal changes elicited by this drug have never been investigated in the transgender population.”

The incidence of self-reported effects among transwomen using MPA and this drug’s impact on hormonal and metabolic parameters were evaluated by retrospectively collecting data from 290 follow-up visits of transwomen treated at Rhode Island Hospital from January 2011 to July 2018 (mean duration of therapy, 3.4±1.7 years).

Participants were treated with oestradiol and spironolactone with (n=102) or without MPA (n=188). Apart from assessing the incidence of self-reported effects after MPA treatment, blood levels of oestradiol, testosterone and various laboratory parameters were also compared between MPA and non-MPA groups.

Mean weighted oestradiol level was similar between MPA and non-MPA groups (211±57 vs 210±31 pg/mL; t[274]=0.143; p=0.886). Mean weighted testosterone level was significantly lower among transwomen treated with MPA than those who did not receive MPA (79±18 vs 215±29 ng/dL; t[122]=32.4; p<0.001). Minimal changes were observed in other laboratory parameters.

Of the 39 patients treated with MPA, 26 reported improved breast development and 11 reported reduced facial hair. On the other hand, five patients reported having mood swings on MPA.

“Prospective studies are needed to confirm our findings,” the investigators said.