From the Guidelines
Estradiol blood levels of 900 pg/ml are generally considered too high for transgender females and should be reduced to safer levels. The recommended target range for estradiol in transgender hormone therapy is typically between 100-200 pg/ml, similar to cisgender women in the mid-follicular phase of their menstrual cycle, as suggested by recent guidelines 1. Levels as high as 900 pg/ml significantly increase health risks, particularly blood clots (venous thromboembolism), stroke, and cardiovascular complications.
Some key points to consider when evaluating estradiol levels in transgender females include:
- The optimal oestradiol doses or concentrations required to induce feminisation are unclear, but most individuals achieve oestradiol and testosterone concentrations in the cisgender female reference range 1
- Feminising hormone therapy induces change in body composition, breast growth, and other physical characteristics, but also carries adverse effects such as an increased risk of venous thromboembolism, weight gain, and cardiovascular disease 1
- Regular blood monitoring is essential for maintaining safe hormone levels, with initial monitoring every 3 months and then every 6-12 months once stable
If you're experiencing these elevated levels, consult your healthcare provider immediately about adjusting your hormone regimen. Your provider may recommend reducing your estradiol dosage or changing the administration method (such as switching from oral to transdermal patches or injections at a lower dose). While some transgender females may feel better subjectively with higher estradiol levels, the increased health risks outweigh potential benefits, and feminization effects typically plateau above the recommended range 1.
From the Research
Estradiol Blood Levels and Safety for Transfemales
- The provided studies do not directly address the safety of estradiol blood levels of 900 pg/ml for transfemales.
- However, study 2 mentions that transfeminine individuals are treated with estradiol and anti-androgen agents to transition to a more feminine appearance, and that adverse effects associated with estradiol use include thromboembolic disease, macroprolactinoma, breast cancer, coronary artery disease, cerebrovascular disease, cholelithiasis, and hypertriglyceridemia.
- Study 3 suggests that in postmenopausal women, a significant reduction of bone resorption is achieved when circulating levels of estradiol reach a value of 60 pg/ml.
- Study 4 found that the minimum concentration of estradiol required to increase bone mineral density was 15 pg/ml, and that higher values of estradiol do not provide additional benefit.
- It is unclear if these findings can be applied to transfemales, as the studies were conducted on postmenopausal women.
- Study 5 compared the anti-androgenic effects of spironolactone and cyproterone acetate in transgender women, and found that cyproterone acetate had a higher testosterone suppression efficacy than spironolactone.
- Study 6 discusses the role of antiandrogens in hormone replacement therapy, but does not provide information on the safety of high estradiol blood levels for transfemales.
Key Findings
- Estradiol blood levels of 60-90 pg/ml may be sufficient to prevent postmenopausal bone loss in women 3.
- The minimum concentration of estradiol required to increase bone mineral density is 15 pg/ml 4.
- Cyproterone acetate has a higher testosterone suppression efficacy than spironolactone in transgender women 5.
- Adverse effects associated with estradiol use include thromboembolic disease, macroprolactinoma, breast cancer, coronary artery disease, cerebrovascular disease, cholelithiasis, and hypertriglyceridemia 2.