From the Guidelines
The penis shrinks in transgender women on estradiol therapy due to a combination of reduced testosterone levels, decreased spontaneous erections, and changes in fat distribution and muscle mass. This physiological change is a common effect of feminizing hormone therapy, which includes oestradiol therapy and anti-androgen medications 1. The reduction in testosterone levels leads to decreased spontaneous erections, causing the erectile tissues to experience disuse atrophy. Additionally, estradiol therapy promotes changes in fat distribution and reduces muscle mass throughout the body, including in the genital region, contributing to penile shrinkage. Key factors influencing the degree of shrinkage include genetics, hormone dosages, and duration of therapy. It is essential to note that while penile shrinkage is a potential effect of estradiol therapy, the benefits of hormone therapy for transgender women, including improved mental health and quality of life, often outweigh the potential risks 1. Regular erectile exercises or gentle stretching may be recommended by medical providers to maintain penile tissue health, especially for those planning future gender-affirming surgeries. Overall, the decision to undergo estradiol therapy should be made in consultation with a healthcare provider, weighing the potential benefits and risks, and considering individual circumstances and priorities. Some studies have reported improvements in quality of life and mental health outcomes following hormone treatment, with minimal evidence of significant regret after gender-affirming treatment 1. However, it is crucial to prioritize individualized care and support to address the unique needs and concerns of each patient. By acknowledging the potential effects of estradiol therapy on penile size and overall health, healthcare providers can work with patients to develop personalized treatment plans that promote optimal physical and emotional well-being.
From the Research
Effects of Estradiol Therapy on Transgender Women
- Estradiol therapy is commonly used in transgender women to achieve feminization, but its effects on the body can be complex and varied 2, 3, 4, 5, 6.
Physiological Changes
- Estradiol therapy can lead to a decrease in testosterone levels, which can result in a range of physiological changes, including changes in body composition, breast development, and genital anatomy 2, 4, 5.
- However, the extent to which these changes occur can vary widely between individuals, and the optimal dosage and duration of estradiol therapy are not well established 2, 4.
Genital Changes
- One of the physiological changes that can occur in transgender women on estradiol therapy is a decrease in the size of the penis, although the exact mechanisms underlying this change are not well understood 3, 5.
- Studies have shown that long-term estradiol therapy can lead to a decrease in testicular volume and weight, as well as a reduction in spermatogenesis 3, 5.
Hormonal Changes
- Estradiol therapy can also lead to changes in hormonal levels, including a decrease in testosterone and an increase in estradiol 2, 4.
- The use of antiandrogens, such as cyproterone acetate or spironolactone, can enhance the effects of estradiol therapy by further reducing testosterone levels 4, 6.