Biochemical Changes During the First Year of Feminizing Hormone Therapy in Transfeminine Individuals

Association between serum estradiol and cardiovascular health among transgender adults using gender-affirming estrogen therapy

Gender-affirming estrogen therapy (GAET) is commonly used for feminization in transgender and nonbinary (TNB) individuals, yet the optimal rate of change (ROC) in estradiol levels for cardiovascular health is unclear. We examined the association between serum estradiol levels and cardiovascular-related mortality, adverse events, and risk factors in TNB adults using GAET. Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE, and Web of Science were systematically searched (inception-April 2023) for original articles reporting serum estradiol levels and cardiovascular-related mortality, adverse events, and risk factors in TNB adults using GAET. Data extraction was completed in duplicate following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Stratified random effect meta-analyses using serum estradiol ROC (serum estradiolbaseline - serum estradiolfollow-up/study duration) was used to assess longitudinal studies (low, 0 < ROC ≤ 1 pg/mL/mo; moderate, 1 < ROC ≤ 3 pg/mL/mo; high, ROC ≥ 3 pg/mL/mo). Thirty-five studies (13 cross-sectional, 19 cohort, and 3 trials) were included. Two studies collectively reported 50 cardiovascular-related deaths, and four collectively reported 23 adverse cardiovascular events. Nineteen studies reporting cardiovascular risk factors were meta-analyzed by ROC stratum (low = 5; moderate = 6; high = 8), demonstrating an association between moderate [0.40, 95% confidence interval (CI): 0.22, 0.59 kg/m2, I2 = 28.2%] and high (0.46, 95% CI: 0.15, 0.78 kg/m2; I2 = 0.0%) serum estradiol ROC and increased body mass index. High (-6.67, 95% CI: -10.65, -2.68 mg/dL; I2 = 0.0%) serum estradiol ROC was associated with decreased low-density lipoproteins. Low (-7.05, 95% CI: -10.40, -3.70 mmHg; I2 = 0.0%) and moderate (-3.69, 95% CI: -4.93, -2.45 mmHg; I2 = 0.0%) serum estradiol ROCs were associated with decreases in systolic blood pressure. In TNB adults using GAET, serum estradiol ROC may influence cardiovascular risk factors, which may have implications for clinical cardiovascular outcomes.NEW & NOTEWORTHY In this systematic review and meta-analysis of 35 studies involving 7,745 participants, high rates of serum estradiol change were associated with small increases in body mass index. Moderate to high rates of change were associated with decreases in low-density lipoprotein. Low rates of change were associated with small decreases in systolic blood pressure. Rate of serum estradiol change in adults using gender-affirming estrogen therapy may influence cardiovascular risk factors, though further research is warranted.

Effectiveness and Safety of Different Estradiol Regimens in Transgender Women (TREAT Study): Protocol for a Randomized Controlled Trial

BACKGROUND

Current guidelines for gender-affirming hormone therapy (GAHT) for transgender women are mostly based on clinical experience from experts in the field and treatments used on postmenopausal women. While care is currently provided with the best available evidence, there is a critical gap in knowledge about the safest and most effective estradiol routes of administration for GAHT in transgender women; this statement is supported by the World Professional Association for Transgender Health on their Standards of Care for the Health of Transgender and Gender Diverse People, version 8. Furthermore, the reported rates of cardiometabolic adverse events in transgender women highlight the importance of investigating changes in lipoproteins, glucose, and insulin sensitivity, among other markers while receiving GAHT.

OBJECTIVE

This study aims to evaluate the degree of testosterone suppression achieved at 1, 6, and 12 months in treatment-naive transgender women when randomized to GAHT with estradiol and spironolactone as antiandrogens. As a secondary aim, this study will assess the treatment effect on metabolic and coagulation factors from baseline to 6 and 12 months after initiating GAHT.

METHODS

This is a prospective pilot, open-label, randomized clinical trial conducted at an adult transgender clinic in a tertiary medical center. The 3 treatment arms include once-daily sublingual 17-β estradiol, twice-daily sublingual 17-β estradiol, and transdermal 17-β estradiol. All participants received spironolactone as an antiandrogen. Transgender women aged 18 to 45 years who are being evaluated for the initiation of GAHT with 17-β estradiol and did not have a history of coagulopathy, cigarette smoking, liver disease, dyslipidemia requiring treatment, or use of gonadotropin-releasing hormone agonist were eligible to enroll. The main outcome is the total testosterone suppression at 1 and 6 months after the initiation of GAHT, and the secondary outcome is to assess treatment effect in a lipid panel; homeostatic model assessment for insulin resistance; coagulation factors II, IX, and XI; Von Willebrand factor; activated protein C resistance; protein C; and protein S at baseline, 6 months, and 12 months after therapy is initiated.

RESULTS

This study was funded in March 2022, and enrollment concluded in August 2022. It was concluded in July 2023, and currently, the results are being analyzed for publication.

CONCLUSIONS

The Transgender Estradiol Affirming Therapy (TREAT) study offers a rigorous and reproducible approach to answer important questions regarding GAHT in transgender women, specifically, the most effective 17-β estradiol regimen to suppress testosterone levels to 50 ng/dL, as currently recommended.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05010707; https://clinicaltrials.gov/study/NCT05010707.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/53092.