Change in Visceral Fat and Total Body Fat and the Effect on Cardiometabolic Risk Factors During Transgender Hormone Therapy

Body composition and risk for sarcopenia in transgender women

OBJECTIVES

Body composition and strength of cisgender (cis) individuals are well established. However, those for transgender women (trans women) undergoing gender-affirming hormone therapy remain unclear. This study aimed to detect possible body composition and strength variations related to sarcopenia.

METHODS

This was a cross-sectional comparative study of 37 trans women, 34 cis men, and 34 cis women. Body composition was measured in all individuals by bioelectrical impedance analysis; prehensile strength by dynamometry was studied in trans women.

RESULTS

In this study, trans women had higher body mass index values than cis individuals (P < 0.01). Fat mass was 41% higher for trans women than cis men. Muscle mass (MM) was lower in trans women than cis men (-10%), and higher than cis women (24%). Bone mass was lower in trans women than cis men and higher in cis women (P < 0.01). Trans women's prehensile strengths were 25.26 kg for the right hand and 24.8 kg for the left. Appendicular skeletal muscle mass was 23.63 kg, and appendicular skeletal muscle mass index was 8.14 kg.

CONCLUSION

Trans women undergoing gender-affirming hormone therapy show a tendency to adapt body compartments to those of cis women with increased fat mass and reduced muscle mass. Prehensile strength in trans women was close to the cutoff points for sarcopenia risk. Nutrition, physical activity, strength, and body composition are important to avoid the possible risk for sarcopenia. More studies along these lines are necessary, especially in older adults.

Effects of gender-affirming hormone therapy on body fat: a retrospective case‒control study in Chinese transwomen

BACKGROUND

There is insufficient research on how gender-affirming hormone therapy (GAHT) affects body fat modifications in transwomen from China. It is unclear whether hormone therapy affects the prevalence of obesity and blood lipid levels within this population. The current research aimed to assess how GAHT and treatment duration had an impact on the change in and redistribution of body fat in Chinese transwomen.

METHODS

This study included 40 transwomen who had not received GAHT and 59 who had. Body fat, blood lipid, and blood glucose levels were measured. GAHT is mainly a pharmacologic (estrogen and anti-androgen) treatment. The study also stratified participants based on the duration of GAHT to assess its impact on body fat distribution. The duration of GAHT was within one year, one to two years, two to three years, or more than three years.

RESULTS

After receiving GAHT, total body fat increased by 19.65%, and the percentage of body fat increased by 17.63%. The arm, corrected leg, and leg regions showed significant increases in fat content (+ 24.02%, + 50.69%, and + 41.47%, respectively) and percentage (+ 25.19%, + 34.90%, and + 30.39%, respectively). The total visceral fat content decreased (-37.49%). Based on the diagnostic standards for a body mass index ≥ 28 or total body fat percentage ≥ 25% or 30%, the chance of developing obesity did not change significantly. Blood glucose levels significantly increased (+ 12.31%). Total cholesterol levels (-10.45%) decreased significantly. Fat changes in those who received GAHT for one to two years were significantly different from those who did not receive GAHT.

CONCLUSION

After receiving GAHT, total body fat and regional fat increased in Chinese transwomen, and the body fat distribution changed from masculine to feminine, especially during the first two years. However, neither the increase in total body fat percentage nor the decrease in visceral fat content didn't bring about significant changes in the incidence of obesity, nor did triglycerides or low-density lipoprotein-cholesterol.

Nutrition research and practice with transgender and gender non-conforming populations

The purpose of the present article is to describe the current state of sex and gender data collection in nutrition science research, discuss the effects of flawed data collection practices, highlight considerations for transgender and gender non-conforming populations and propose a sex- and gender-informed approach to human subjects research. Sex and gender are separate constructs that are often conflated in nutrition research and practice. Current nutrition surveillance programmes in the United States, United Kingdom and Ireland do not accurately capture sex and gender data, which undermines the accuracy of the analyses and excludes gender minorities. Transgender and gender non-conforming populations have distinct clinical and psychosocial nutrition considerations that require further research to inform nutrition policy and practice, such as anthropometric and biochemical changes with hormone therapy, eating disorders, food insecurity and nutrition as a source of empowerment or expression of gender identity. Researchers can apply a sex- and gender-informed approach to human subjects research by treating sex and gender as separate, relevant demographic data, appreciating gender as a fluid construct, and approaching data collection on gender minorities with sensitivity to privacy and confidentiality.

Incidence of Type 2 Diabetes Mellitus in Transgender Individuals Undergoing Gender Affirming Hormonal Therapy: A Systematic Review

Gender-affirming hormonal therapy (GAHT), which includes estrogen, testosterone, androgen agonists, is commonly used in transgender individuals to change their secondary sexual characteristics to align with their gender identity. However, this treatment could result in metabolic side effects that could increase the chances of acquiring type 2 diabetes mellitus. Thus, this study aims to compare differences in body mass index (BMI), insulin resistance, and the incidence of type 2 diabetes mellitus between cisgender and transgender individuals undergoing GAHT. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards, we conducted a systematic review searching through PubMed, Google Scholar, Medline (Medical Literature Analysis and Retrieval System Online), and ResearchGate for articles published between 2014 and 2024. The final search was conducted in February 2024. Out of the 3,934 articles reviewed, 11 were selected, focusing on insulin sensitivity/resistance, diabetes incidence, and BMI changes with GAHT. Although our result findings did not show clear evidence of increased diabetes incidence among GAHT patients, it was observed that GAHT does increase BMI and insulin resistance in transgender individuals. Notably, compared to transgender men, transgender women on GAHT were found to be more prone to insulin resistance. We recommend regularly monitoring insulin sensitivity parameters and HbA1c during GAHT to monitor metabolic side effects. Further research and more clinical trials are needed to confirm the GAHT's impact on insulin resistance and to evaluate its role in the onset of type 2 diabetes mellitus.

A European Network for the Investigation of Gender Incongruence in adolescents

BACKGROUND

Knowledge regarding the effects and side effects of gender-affirming hormone therapy (GAHT) in adults is rapidly growing, partly through international research networks such as the European Network for the Investigation of Gender Incongruence (ENIGI). However, data on the effects of puberty suppression (PS) and GAHT in transgender and gender diverse (TGD) youth are limited, although these data are of crucial importance, given the controversies surrounding this treatment.

AIM

We sought to present a detailed overview of the design of the ENIGI Adolescents study protocol, including the first baseline data.

METHODS

The ENIGI Adolescents study is an ongoing multicenter prospective cohort study. This study protocol was developed by 3 European centers that provide endocrine care for TGD adolescents and were already part of the ENIGI collaboration: Amsterdam, Ghent, and Florence.

OUTCOMES

Study outcomes include physical effects and side effects, laboratory parameters, bone mineral density, anthropometric characteristics, attitudes toward fertility and fertility preservation, and psychological well-being, which are measured in the study participants during PS and GAHT, up to 3 years after the start of GAHT.

RESULTS

Between November 2021 and May 2023, 172 TGD adolescents were included in the ENIGI Adolescents protocol, of whom 51 were assigned male at birth (AMAB) and 121 were assigned female at birth (AFAB); 3 AFAB participants reported a nonbinary gender identification. A total of 76 participants were included at the start of PS, at a median (IQR) age of 13.7 (12.9-16.5) years in AMAB and 13.5 (12.4-16.1) years in AFAB individuals. The remaining 96 participants were included at start of GAHT, at a median (IQR) age of 15.9 (15.1-17.4) years in AFAB and 16.0 (15.1-16.8) years in AMAB individuals. At the time of this report the study was open for inclusion and follow-up measurements were ongoing.

CLINICAL IMPLICATIONS

In response to the rising demand for gender-affirming treatment among TGD youth, this ongoing study is fulfilling the need for prospective data on the effects and safety of PS and GAHT, thus providing a foundation for evidence-based healthcare decisions.

STRENGTHS AND LIMITATIONS

This study has a strong multicenter, prospective design that allows for systematic data collection. The use of clinical and self-reported data offers a broad range of outcomes to evaluate. Nevertheless, the burden of additional measurements and questionnaires may lead to withdrawal or lower response rates. Few participants with a non-binary gender identity have been included.

CONCLUSION

With the ENIGI Adolescents study we aim to create a comprehensive dataset that we can use for a wide range of studies to address current controversies and uncertainties and to improve healthcare for TGD adolescents.

Adipokine secretion and lipolysis following gender-affirming treatment in transgender individuals

BACKGROUND

The organ-specific effects of gender-affirming sex hormone treatment (GAHT) in transgender women (TW) and transgender men (TM) are insufficiently explored. This study investigated the effects of GAHT on adipose tissue function.

METHODS

In a single-center interventional prospective study, 32 adults undergoing GAHT, 15 TW and 17 TM, were examined with anthropometry and abdominal subcutaneous adipose tissue biopsies obtained before initiation of treatment, 1 month after endogenous sex hormone inhibition and three and 11 months after initiated GAHT. Fat cell size, basal/stimulated lipolysis and cytokine secretion in adipose tissue were analyzed.

RESULTS

TW displayed an increase in complement component 3a and retinol-binding protein 4 (RBP4) secretion after sex hormone inhibition, which returned to baseline following estradiol treatment. No changes in lipolysis were seen in TW. TM showed downregulation of RBP4 after treatment, but no changes in basal lipolysis. In TM, the estrogen suppression led to higher noradrenaline stimulated (NA) lipolysis that was normalized following testosterone treatment. At 11 months, the ratio of NA/basal lipolysis was lower compared to baseline. There were no significant changes in fat cell size in either TW or TM.

CONCLUSION

In TW, gonadal hormone suppression results in transient changes in cytokines and in TM there are some changes in NA-stimulated lipolysis following testosterone treatment. However, despite the known metabolic effects of sex hormones, the overall effects of GAHT on adipose tissue function are small and likely have limited clinical relevance, but larger studies with longer follow-up are needed to confirm these findings.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02518009, Retrospectively registered 7 August 2015.

Persistent vaginal bleeding during gender-affirming hormone therapy in transgender men

PURPOSE

While it is common for menstrual cycles to cease within the initial 6 months of treatment, there are instances where some transgender men may not experience this cessation. We analyzed transgender men undergoing gender-affirming hormone therapy (GAHT) with testosterone who experienced breakthrough bleeding in order to identify the factors associated with this condition.

METHODS

In this case-control study, 24 transgender men in the case group and 48 in the control group were assessed for clinical, sociodemographic, hormonal, and body composition variables using dual-energy X-ray absorptiometry. All participants had been on GATH for at least 6 months.

RESULTS

A few transgender men experienced persistent breakthrough bleeding, which was associated with decreased testosterone levels and free androgen index (FAI) compared with controls (p = 0.002 and p = 0.008, respectively). Among individuals with breakthrough bleeding, 50% had testosterone levels below the lowest tertile calculated for the sample, compared with 18.8% on controls (p = 0.007). After therapy adjustment, testosterone levels increased compared with the values obtained in the initial bleeding episode (p = 0.031). Eight transgender men required the addition of an oral progestogen to achieve amenorrhea, and these individuals had higher BMI than those in whom the adjustment of the parenteral testosterone dose was adequate (p = 0.026). A univariate prevalence ratio analysis revealed a negative association of persistent bleeding with testosterone levels (p = 0.028) and FAI levels (p = 0.019).

CONCLUSION

Higher BMI and lower levels of testosterone and FAI were the main factors associated with breakthrough bleeding in transgender men.

Sex Steroids Regulate Liver Fat Content and Body Fat Distribution in Both Men and Women: A Study in Transgender Persons

CONTEXT

Liver fat content and visceral fat volume are associated with insulin resistance and cardiovascular disease and are higher in men than in women.

OBJECTIVE

To determine the effect of estradiol and testosterone treatment on liver fat and visceral fat in transgender persons.

DESIGN

Open-label intervention study (SHAMVA) with a 1-year follow-up.

SETTING

Gender clinic in a hospital.

PATIENTS

8 trans women and 18 trans men receiving hormone treatment.

INTERVENTIONS

Trans women received an antiandrogen and after 6 weeks estradiol was added. Trans men were randomized to receive triptorelin, testosterone, and anastrozole for 12 weeks or triptorelin and testosterone for 12 weeks, followed by only testosterone until week 52.

MAIN OUTCOME MEASURES

Liver fat content, visceral and abdominal subcutaneous fat volume, measured by magnetic resonance spectrometry or imaging at baseline, 6, 8, 18, and 58 weeks in transwomen or at baseline; at 6 and 12 weeks in trans men with anastrozole; and at 52 weeks in trans men without anastrozole.

RESULTS

In trans women, liver fat content decreased by 1.55% (-2.99 to -0.12) after 58 weeks, compared to week 6. Visceral fat did not change. In trans men with anastrozole, the liver fat content and visceral fat volume did not change. In trans men without anastrozole, after 52 weeks, liver fat content increased by 0.83% (0.14 to 1.52) and visceral fat volume increased by 34% (16 to 51).

CONCLUSIONS

Sex hormones regulate liver fat content and visceral fat in men and women.

Nutrition and Health in the Lesbian, Gay, Bisexual, Transgender, Queer/Questioning Community: A Narrative Review

Sexual and gender minorities have a higher risk for health and nutrition-related disparities across the life course compared to the heterosexual or cisgender population. Experiences of stigmatization and discrimination are associated with diminished mental health quality and psychological distress, which are risk factors for developing various eating disorders. Other nutrition disparities include increased risk for food insecurity, body dissatisfaction, and weight complications, such as those experienced by the transgender population in association with gender-affirming hormone therapies. Despite the need for tailored nutrition recommendations that address the unique needs of the lesbian, gay, bisexual, transgender, queer/questioning (LGBTQ+) community, there are currently no such guidelines in North America. The purpose of this review is to summarize major LGBTQ+ nutrition disparities and highlight the need for tailored recommendations. We examine the evidence on mental health and social disparities in this group, including vulnerabilities to disordered eating, food insecurity, and healthcare provider discrimination. Importantly, we identify a scarcity of literature on dietary concerns and nutrition care guidelines for LGBTQ+ groups, including studies that address intersectionality and differences among specific gender and sexual orientations. These gaps underline the urgency of prioritizing nutrition for LGBTQ+ health needs and for developing tailored public health nutrition recommendations for this underserved population. Our review suggests that future LGBTQ+ health and nutrition research agendas should include personalized and precision nutrition, social determinants of health, diet quality, body image, and healthcare provider cultural competency and responsiveness. Moreover, the current evidence on LGBTQ+ nutrition and health will be strengthened when research studies (including clinical trials) with robust methodologies amplify inclusion and representation of this community to elucidate health and nutrition disparities in sexual and gender minorities.

Insights Into the Cardiomodulatory Effects of Sex Hormones: Implications in Transgender Care

Transgender individuals that undergo gender-affirming hormone therapy may experience discrimination in the health care setting with a lack of access to medical personnel competent in transgender medicine. Recent evidence suggests that gender-affirming hormone therapy is associated with an increased risk of cardiovascular diseases and cardiovascular risk factors. A recent statement from the American Heart Association reinforces the importance of cardiovascular-focused clinical management and the necessity for more research into the impact of gender-affirming hormone therapy. With this in mind, this review will highlight the known cardiovascular risk factors associated with gender-affirming hormone therapy and identify potential molecular mechanisms determined from the limited animal studies that explore the role of cross-sex steroids on cardiovascular risk. The lack of data in this understudied population requires future clinical and basic research studies to inform and educate clinicians and their transgender patient population to promote precision medicine for their care to improve their quality of life.

Gender-affirming hormonal therapy for transgender and gender-diverse people-A narrative review

As the number of transgender and gender-diverse (TGD) people accessing gender-affirming care increases, the need for healthcare professionals (HCPs) providing gender-affirming hormonal therapy (GAHT) also increases. This chapter provides an overview of the HCPs interested in getting involved in providing GAHT.

Update in Adult Transgender Medicine

Transgender people often face barriers in health care due to lack of access to care, lack of knowledgeable healthcare professionals, discrimination, and gaps in medical and mental health research. Existing research on transgender health has focused heavily on mental health, HIV/AIDS, sexually transmitted diseases/infections, and substance abuse. Gender-affirming hormone therapy and/or surgery allows for some alignment of biology and gender identity. Gender-affirming care may offer quality-of-life benefits, which may outweigh modest concerns related to exogenous hormone therapy. The Endocrine Society treatment guidelines were revised in 2017, and this article reviews recent data that might inform a future guideline revision. Future longitudinal research is needed to close the gap in knowledge in the field of transgender medicine.

Gender-affirming hormone therapy, mental health, and surgical considerations for aging transgender and gender diverse adults

As the transgender and gender diverse (TGD) population ages, more transfeminine and transmasculine individuals present to clinic to initiate or continue their gender-affirming care at older ages. Currently available guidelines on gender-affirming care are excellent resources for the provision of gender-affirming hormone therapy (GAHT), primary care, surgery, and mental health care but are limited in their scope as to whether recommendations require tailoring to older TGD adults. Data that inform guideline-recommended management considerations, while informative and increasingly evidence-based, mainly come from studies of younger TGD populations. Whether results from these studies, and therefore recommendations, can or should be extrapolated to aging TGD adults remains to be determined. In this perspective review, we acknowledge the lack of data in older TGD adults and discuss considerations for evaluating cardiovascular disease, hormone-sensitive cancers, bone health and cognitive health, gender-affirming surgery, and mental health in the older TGD population on GAHT.

Fit Transitioning: When Can Transgender Airmen Fitness Test in Their Affirmed Gender?

INTRODUCTION

Transgender individuals have served openly in the U.S. Military since 2016. Official policies for transgender servicemembers continue to evolve, including approaches to physical fitness testing of transgender servicemembers. There is a paucity of scientific data regarding the effects of gender affirming hormone therapy (GAHT) on athletic performance for the past 24 months of treatment. Identification of expected trends in performance during and after gender transition is essential to allow for the development of appropriate military policy regarding when to assess servicemembers' fitness by standards of their affirmed gender.

MATERIALS AND METHODS

We identified Department of the Air Force transgender patients using the Transgender Health Medical Evaluation Unit database and recorded dates of GAHT initiation through a retrospective chart review. We recorded performance values for the Air Force physical fitness test components 1 year before and up to 4 years after GAHT initiation. Performance measures were maximum sit-ups in 1 minute, push-ups in 1 minute, and 1.5-mile run time. Pre- and post-GAHT scores were compared using one-sample T-test to mean scores of Air Force-wide cisgender averages to assess for significant difference between affirmed transgender and cisgender airmen. We then performed the two one-sided test (TOST) procedure for equivalence with upper and lower bounds set at 1 SD from the means for cisgender airmen. Finally, using Z-scores, average transgender group scores were assigned a percentile rank with their respect to affirmed gender throughout the transition process.

RESULTS

Following initiation of GAHT, transgender males demonstrated statistically significant worse performance than cisgender males in all events until 3 years of GAHT. Their average scores would have attained a comfortable passing score within 1 year of GAHT. Transgender females' performance showed statistically significantly better performance than cisgender females until 2 years of GAHT in run times and 4 years in sit-up scores and remained superior in push-ups at the study's 4-year endpoint. TOST confirmed equivalence at all points where statistical difference was not demonstrated. Servicemembers approximate their pre-GAHT assigned gender percentile ranking in their affirmed gender in a manner consistent with hypothesis and TOST testing in the push-up event for both transgender males and females and in the 1.5-mile run event for transgender males.

CONCLUSIONS

In a sample of Air Force adult transgender patients, athletic performance measures demonstrate variable rates of change depending on the patients' affirmed gender and differ by physical fitness test component. Based on this study, transgender females should begin to be assessed by the female standard no later than 2 years after starting GAHT, while transgender males could be assessed by their affirmed standard no earlier than 3 years after initiating GAHT.

Effects of gender-affirming hormone therapy on cardiovascular risk factors focusing on glucose metabolism in an Austrian transgender cohort

Objective

We aimed to investigate the effect of gender-affirming hormone therapy (GAHT) on cardiovascular disease risk factors focusing on glucose tolerance.

Patients and Methods

This primarily translational study enrolled 16 transgender persons assigned female at birth (AFAB), 22 assigned male at birth (AMAB), and 33 age- and BMI-matched cisgender controls at the Medical University of Vienna from 2013 to 2020. A 3-Tesla MRI scan to measure intramyocardial, pancreatic, hepatic fat content and subcutaneous-to-visceral adipose tissue ratio (SAT/VAT-ratio), an oral glucose tolerance test (oGTT), bloodwork including brain natriuretic peptide (pro-BNP), sex hormones and two glucose-metabolism related biomarkers (adiponectin, betatrophin) were performed.

Results

Estrogen intake was associated with higher fasting insulin (p = 0.034) and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (p = 0.037), however, lower HbA1c levels (p = 0.031) in AMAB than cisgender males. Adiponectin (p = 0.001) and betatrophin (p = 0.034) levels were higher in AMAB than cisgender males, but similar to cisgender females. Compared to cisgender females, AFAB displayed no differences in glucose metabolism or SAT/VAT-ratio. AFAB had lower pro-BNP levels (p = 0.014), higher liver enzymes (AST: p = 0.011; ALT: p = 0.012) and lower HDL levels (p = 0.017) than cisgender females, but comparable levels to cisgender males. AMAB showed an increased heart rate (p < 0.001) and pro-BNP (p = 0.002) levels, but a more favorable SAT/VAT-ratio (p = 0.013) and lower creatine kinase (CK) (p = 0.001) than cisgender males. There were no relevant differences in organ fat content between transgender persons and their respective cisgender controls.

Conclusion

In AMAB, most investigated parameters adapted to levels seen in cisgender females except for parameters related to fasted insulin resistance. AMAB should be monitored with respect to the development of insulin resistance.

Anti-osteoporosis treatments changed body composition in postmenopausal women: A systematic review and meta-analysis

BACKGROUND

Whether the widespread anti-osteoporosis treatments in postmenopausal women also benefit the change of body composition (lean body mass [LBM] and body fat mass [FM]) remains controversial. In order to solve this issue and find out the most effective treatment, we conducted this meta-analysis.

METHODS

We searched the literature, via PubMed, Embase, Scopus, Web of Science, and Cochrane to screen citations from inception to March 26, 2022, for inclusion in this study. Only clinical trials that used anti-osteoporosis treatments in postmenopausal women and displayed the alteration of body composition were included. Stata 14.0 was used for the meta-analysis.

RESULTS

Our meta-analysis results presented that: compared with placebo, hormone replacement therapy (HRT) was associated with increased LBM (standardized mean differences [SMD] = 0.32, 95% confidence interval [CI] = 0.02-0.61) and reduced FM (SMD = -0.30, 95% CI = -0.51 to -0.09) in postmenopausal women. Compared with placebo, physical exercise training showed an effect of decreasing FM (SMD = -0.66, 95% CI = -0.94 to -0.38) but not significant influence LBM (SMD = 1.31, 95% CI = -0.29 to 2.91). The network meta-analysis of our study showed that oral estrogen and progestogen plus exercise (OEPE) treatment might be the most effective anti-osteoporosis treatment (surface under the cumulative ranking curve 99.9) to reduce FM in postmenopausal women.

CONCLUSIONS

anti-osteoporosis treatments, especially HRT, affect body composition. Furthermore, the combination of HRT and exercise training are the most effective treatment to reduce FM while maintaining LBM.

Incident Diabetes Risk Is Not Increased in Transgender Individuals Using Hormone Therapy

CONTEXT

In trans women receiving hormone therapy, body fat and insulin resistance increases, with opposite effects in trans men. These metabolic alterations may affect the risk of developing type 2 diabetes in trans women and trans men.

CONTEXT

We aimed to compare the incidence of type 2 diabetes of adult trans women and trans men during hormone therapy with rates from their birth-assigned sex in the general population.

METHODS

Retrospective data from the Amsterdam Cohort of Gender Dysphoria with transgender individuals on hormone therapy between 1972 and 2018 were linked to a nationwide health data registry. Because no central registry of diabetes is available, the occurrence of diabetes was inferred from the first dispense of a glucose-lowering agent. Standardized incidence ratios (SIR) were computed for trans women and trans men in comparison with the same birth sex from the general population.

RESULTS

Compared with their birth-assigned sex in the general population, no difference in the incidence of type 2 diabetes mellitus was observed in trans women (N = 2585, 90 cases; SIR 0.94; 95% CI, 0.76-1.14) or trans men (N = 1514, 32 cases; SIR 1.40; 95% CI, 0.96-1.92).

CONCLUSION

Despite studies reporting an increase in insulin resistance in feminizing hormone therapy and a decrease in insulin resistance in masculinizing hormone therapy, the incidence of diabetes in transgender individuals after initiation of hormone therapy was not different compared with the general population.

The Role of Estrone in Feminizing Hormone Treatment

CONTEXT

In trans women, hormone treatment induces feminization; however, the degree of feminization varies from person to person. A possible contributing factor could be estrone, a weak estrogen that interferes with the estrogen receptor.

OBJECTIVE

We assessed whether estrone is involved in feminization induced by hormone treatment.

METHODS

This prospective cohort study, with follow-up of 1 year, included 212 adult trans women at a gender identity clinic, who were starting gender-affirming hormone treatment between July 2017 and December 2019, median age 25 years. Change in fat percentage and breast development were assessed.

RESULTS

After 12 months of hormone treatment, estrone concentration was 187 pmol/L (95% CI, 153-220) in transdermal and 1516 pmol/L (95% CI, 1284-1748) in oral estradiol users. Fat percentage increased by 1.2% (interquartile range [IQR], 0.3-4.8) in transdermal and 4.6% (IQR, 2.5-5.9) in oral estradiol users. This was not associated with estrone concentrations in transdermal (+4.4% (95% CI, -4.0 to 13) per 100 pmol/L increase in estrone concentration) nor in oral estradiol users (-0.7% [95% CI, -1.7 to 0.3]). Breast volume increased by 69 mL (IQR, 58-134) in transdermal and 62 mL (IQR, 32-95) in oral estradiol users. This was not associated with estrone concentrations in transdermal (+14% [95% CI, -49 to 156] per 100 pmol/L increase in estrone concentration) nor oral estradiol users (+11% [95% CI -14 to 43]).

CONCLUSIONS

Change in fat percentage and breast development in trans women were not associated with estrone concentrations nor with administration route. Therefore, measurement of estrone concentrations does not have a place in the monitoring of feminization in trans women.