From the Guidelines
Yes, micronized progesterone can be prescribed alongside estrogen and cyproterone acetate in transgender hormone therapy for transfeminine individuals, as it may help with breast development, mood stabilization, and libido, with a favorable safety profile compared to synthetic progestogens 1.
Key Considerations
- A typical regimen might include estradiol (in forms such as oral tablets 2-6mg daily, transdermal patches 100-200mcg/day, or injectable estradiol valerate 5-20mg every 1-2 weeks), cyproterone acetate (10-25mg daily), and micronized progesterone (100-200mg daily, often taken at bedtime) 1.
- Progesterone is typically added after 1-2 years of estrogen therapy, as this mimics natural female puberty timing.
- When prescribing this combination, monitor for side effects including mood changes, fatigue, and increased risk of venous thromboembolism.
- Regular follow-up should include liver function tests due to cyproterone's potential hepatotoxicity, as well as hormone level monitoring, metabolic panels, and cardiovascular risk assessment 1.
Benefits and Risks
- Micronized progesterone has a favorable safety profile compared to synthetic progestogens, with a lower risk of cardiovascular events and thrombotic risk 1.
- The combination of estrogen and progesterone may provide sufficient testosterone suppression with potentially fewer long-term risks, allowing for the eventual discontinuation of cyproterone acetate.
- However, evidence for the benefits of progesterone in transgender care is limited, and further studies are needed to fully understand its effects 1.
Clinical Decision-Making
- Clinicians should choose between a sequential and continuous regimen of administration, with the latter preventing withdrawal bleeding 1.
- The dose of progestogen is based on the concurrent dose of estrogen administered, and clinicians should consider the individual patient's needs and medical history when prescribing hormone therapy 1.
From the Research
Prescribing Progesterone with Oestrogen and Cyproterone in Transgender Care
- The use of progesterone in gender-affirming therapy for trans women is explored in a study 2, which suggests that progesterone may exert moderate anti-androgen action and contribute to breast maturation.
- However, the study also notes that the potential benefits of progesterone are mainly inferred by extrapolating evidence from biological actions in cisgender women and medical assumptions, and further research is needed to ascertain the efficacy and safety of progesterone in current hormonal regimens.
- Another study 3 compares the anti-androgenic effects of cyproterone acetate and spironolactone in transgender women, and finds that cyproterone acetate has a higher testosterone suppression efficacy than spironolactone.
- A randomized clinical trial 4 assesses the effect of spironolactone and cyproterone acetate on breast growth in transgender people, and finds that there is no significant difference in breast development between the two groups.
- A historical cohort study 5 evaluates the effectiveness and safety of low-dose cyproterone acetate treatment for transgender women, and suggests that low-dose treatment is as effective as high-dose treatment and possibly safer.
- A review article 6 provides guidance on acute clinical care for transgender patients, including managing hormone therapy and other clinical issues, and emphasizes the importance of using patient-identified names and pronouns, and obtaining a surgical history inclusive of an anatomic inventory.
Considerations for Prescribing
- When prescribing progesterone with oestrogen and cyproterone in transgender care, clinicians should consider the potential benefits and risks of each medication, as well as the individual patient's needs and medical history.
- The choice of anti-androgen should be based on clinician and patient preference, with consideration of side effects 4.
- Clinicians should also be aware of the potential interactions between hormone therapy and other medications, as well as the unique needs of transgender patients in the hospital setting 6.