From the Guidelines
A low Dihydrotestosterone (DHT) level in a transgender woman on estrogen therapy indicates effective suppression of androgens, which is a desired outcome of hormone therapy, as evidenced by the most recent update in adult transgender medicine 1. This suggests that the current hormone regimen is successfully blocking testosterone conversion to DHT, which is important for reducing masculine physical characteristics.
- The typical regimen for transgender women includes estrogen and an adjunct antiandrogen, such as spironolactone, cyproterone acetate, or gonadotropin-releasing hormone, to enable lower doses of estrogen to be used 1.
- Lower testosterone levels in the setting of adult levels of estradiol can produce typically feminine physical attributes, such as increased breast development, decreased facial/body hair, and feminized body shape/composition 1.
- If DHT levels are low, no medication adjustment is likely needed for androgen suppression, but complete hormone assessment should include measuring total testosterone, estradiol, and monitoring other health parameters.
- Low DHT levels help reduce masculine hair patterns, prevent male-pattern baldness, and may slow body hair growth, all of which contribute to physical feminization.
- Regular monitoring of hormone levels every 3-6 months is recommended to ensure continued effectiveness of the hormone regimen while minimizing potential health risks, as supported by the latest research in the field 1.
From the Research
Dihydrotestosterone (DHT) Levels in Transgender Women on Estrogen Therapy
- A low DHT level in a transgender woman on estrogen therapy may indicate effective suppression of endogenous testosterone production, which is a goal of gender-affirming hormone therapy (GAHT) 2, 3.
- Testosterone suppression is typically achieved through the use of estradiol and antiandrogens such as spironolactone 2, 4.
- The effectiveness of testosterone suppression can vary among individuals, with some studies suggesting that up to a quarter of transgender women on GAHT may experience nonsuppressed testosterone levels 5.
- Factors contributing to nonsuppressed testosterone levels can include patient, medication, laboratory, and organ-specific concerns, and a stepwise approach may be necessary to determine the etiology and adjust the feminizing hormonal therapy regimen accordingly 5.
Testosterone Suppression in Transgender Women
- Studies have shown that transdermal 17-beta estradiol can result in more rapid suppression of total testosterone compared to sublingual estradiol 2.
- The use of spironolactone as an antiandrogen can also contribute to effective testosterone suppression 2, 3.
- Testosterone levels can vary among individuals, with some studies suggesting that patients with normal body mass index (BMI) may have higher testosterone levels, while those with obese BMI may have lower testosterone levels throughout treatment 3.
Feminizing Hormone Treatment in Transgender Women
- Feminizing hormonal treatment for transgender women typically includes natural estrogen (estradiol) and may involve additional testosterone-blocking treatment such as cyproterone acetate, gonadotropin-releasing hormone agonist (GnRH-a), or spironolactone 6.
- The health risks of cyproterone acetate as anti-androgen treatment are debated, and randomized protocols with other anti-androgen treatments are requested 6.
- Orchiectomy may be performed in some transgender women after various durations of GAHT, and natural progesterone is not currently recommended as part of GAHT due to limited knowledge on the balance between risks and benefits 6.