Cross-sex Hormone Research Articles

Chronotype changes after sex hormone use: A prospective cohort study in transgender users of gender-affirming hormones

ABSTRACT Chronotype, an individual’s preferred sleep-wake timing, is influenced by sex and age. Men sometimes report a later chronotype than women and older age is associated with earlier chronotype. The sex-related changes in chronotype coincide with puberty and menopause. However, the effects of sex hormones on human chronotype remain unclear. To examine the impact of 3 months of gender-affirming hormone therapy (GAHT) on chronotype in transgender persons, this study used data from 93 participants from the prospective RESTED cohort, including 49 transmasculine (TM) participants starting testosterone and 44 transfeminine (TF) participants starting estrogens and antiandrogens. Midpoint of sleep and sleep duration were measured using the ultra-short Munich ChronoType Questionnaire (µMCTQ). After 3 months of GAHT, TM participants’ midpoint of sleep increased by 24 minutes (95% CI: 3 to 45), whereas TF participants’ midpoint of sleep decreased by 21 minutes (95% CI: −38 to −4). Total sleep duration did not change significantly in either group. This study provides the first prospective assessment of sex hormone use and chronotype in transgender persons, showing that GAHT can change chronotype in line with cisgender sex differences. These findings provide a basis for future studies on biological mechanisms and clinical consequences of chronotype changes.

Impact of Distinct Antiandrogen Exposures on the Plasma Metabolome in Feminizing Gender-affirming Hormone Therapy.

The plasma metabolome is a functional readout of metabolic activity and is associated with phenotypes exhibiting sexual dimorphism, such as cardiovascular disease. Sex hormones are thought to play a key role in driving sexual dimorphism. Gender-affirming hormone therapy (GAHT) is a cornerstone of transgender care, but longitudinal changes in the plasma metabolome with feminizing GAHT have not been described. Blood samples were collected at baseline and after 3 and 6 months of GAHT from transgender women (n = 53). Participants were randomized to different anti-androgens, cyproterone acetate or spironolactone. Nuclear magnetic resonance-based metabolomics was used to measure 249 metabolic biomarkers in plasma. Additionally, we used metabolic biomarker data from an unrelated cohort of children and their parents (n = 3748) to identify sex- and age-related metabolite patterns. We identified 43 metabolic biomarkers altered after 6 months in both anti-androgen groups, most belonging to the very low- or low-density lipoprotein subclasses, with all but 1 showing a decrease. We observed a cyproterone acetate-specific decrease in glutamine, glycine, and alanine levels. Notably, of the metabolic biomarkers exhibiting the most abundant "sex- and age-related" pattern (higher in assigned female children and lower in assigned female adults, relative to assigned males), 80% were significantly lowered after GAHT, reflecting a shift toward the adult female profile. Our results suggest an anti-atherogenic signature in the plasma metabolome after the first 6 months of feminizing GAHT, with cyproterone acetate also reducing specific plasma amino acids. This study provides novel insight into the metabolic changes occurring across feminizing GAHT.

Gender affirming hormone therapy and transgender women fertility: Histologic predictors of germ cell presence.

Evaluate histological changes in testicular parameters after hormone treatment in transgender women. Cross-section study with patients who underwent gonadectomy at Hospital de Clínicas de Porto Alegre from 2011 to 2019. Hormone treatment type, route of administration, age at initiation and duration were recorded. Atrophy parameters were observed: testicular volume, tubular diameter, basal membrane length, presence of spermatogonia and spermatids (diploid and haploid spermatozoid precursors). Eighty-six patients were included. Duration of hormone treatment is associated with testicular atrophy and spermatogenesis arrest. Other characteristics of hormone treatment such as age of initiation, route of administration and type of treatment were not associated with testicular histological changes. Testicular volume may predict spermatogenesis arrest. Basal membrane length and tubular diameter ratio is an interesting predictor of germ cell presence. Cross-sex hormone treatment affects testicular germ cell presence. Basal membrane length and tubular diameter ratio reduces inter variability of measurements and better exemplify how atrophic seminiferous tubules are. Fertility preservation should be addressed by healthcare providers in order to recognize gender affirming treatment impact on transgender health.

The impact of gender-affirming hormone therapy on nutrition-relevant biochemical measures.

Gender-affirming hormone therapy carries the potential risk for shifts in biochemical markers that may impact cardiometabolic, hematologic, hepatic, and renal health. The critical evaluation of biochemical data is an integral part of a comprehensive nutrition assessment; therefore, nutrition professionals should be aware of shifts that are expected during the course of masculinizing and feminizing hormone therapy. Changes in important biochemical values along with binary sex-specific standards for interpreting laboratory data can pose significant challenges for nutrition professionals working with transgender and gender-diverse patients who receive gender-affirming hormone therapy. Overall, research on the biochemical impact of masculinizing and feminizing hormone therapy is nascent and limited. Methodologies and outcomes measured are heterogenous across studies, introducing complexities that impede researchers from drawing definitive conclusions. In light of these limitations, this narrative review aims to describe the potential implications of masculinizing and feminizing hormone therapy regimens on biochemical measures that may influence nutrition strategies and interventions to promote optimal health.

Laboratory Changes During Gender-Affirming Hormone Therapy in Transgender Adolescents.

Guidelines for monitoring of medications frequently used in the gender-affirming care of transgender and gender-diverse (TGD) adolescents are based on studies in adults or other medical conditions. In this study, we aimed to investigate commonly screened laboratory measurements in TGD adolescents receiving gender-affirming hormone therapy (GAHT). TGD adolescents were recruited from 4 study sites in the United States before beginning GAHT. Hemoglobin, hematocrit, hemoglobin A1c, alanine transaminase, aspartate aminotransferase, prolactin, and potassium were abstracted from the medical record at baseline and at 6, 12, and 24 months after starting GAHT. Two-hundred and ninety-three participants (68% designated female at birth) with no previous history of gonadotropin-releasing hormone analog use were included in the analysis. Hemoglobin and hematocrit decreased in adolescents prescribed estradiol (-1.4 mg/dL and -3.6%, respectively) and increased in adolescents prescribed testosterone (+1.0 mg/dL and +3.9%) by 6 months after GAHT initiation. Thirteen (6.5%) participants prescribed testosterone had hematocrit > 50% during GAHT. There were no differences in hemoglobin A1c, alanine transaminase, or aspartate aminotransferase. There was a small increase in prolactin after 6 months of estradiol therapy in transfeminine adolescents. Hyperkalemia in transfeminine adolescents taking spironolactone was infrequent and transient if present. Abnormal laboratory results are rare in TGD adolescents prescribed GAHT and, if present, occur within 6 months of GAHT initiation. Future guidelines may not require routine screening of these laboratory parameters beyond 6 months of GAHT in otherwise healthy TGD adolescents.

Trans men can achieve adequate muscular development through low-dose testosterone therapy: A long-term study on body composition changes.

Transgender individuals undergo the gender-affirming hormone therapy (GAHT) to achieve physical changes consistent with their gender identity. Few studies are available on the long-term safety and efficacy of GAHT. To investigate the long-term physical effects and the safety of the testosterone therapy for trans men and to assess the impact of differential hormone dose. Trans men who initiated GAHT between May 2000 and December 2021 were included in this retrospective analysis. Physical findings (body mass index, body fat percentage (BFP), lean body mass (LBM), and grip strength), blood testing results (hemoglobin, hematocrit, uric acid, creatinine, total cholesterol, triglycerides, and total testosterone), and menstrual cessation were recorded. We assessed the effects of testosterone on body composition changes and laboratory parameters, comparing a low-dose group (≤ 62.5mg/wk) to a high-dose group(>62.5mg/wk). Of 291 participants, 188 patients (64.6%) were in the low-dose group and 103 (35.4%) in the high-dose group. Cumulative menstrual cessation rates up to 12 months were not significantly different between groups. Both groups showed a decrease in BFP and an increase in LBM during the first year of therapy, followed by a slight increase in both over the long term. The high-dose group exhibited greater LBM gains during the first year. Higher hormone doses and lower initial LBM values were associated with LBM increases at 3 and 6 months (3mo, P=0.006, P<0.001; 6mo, P=0.015, P<0.001). There were no long-term, dose-dependent side effects such as polycythemia or dyslipidemia. Long-term GAHT for trans men is safe and effective. Low-dose testosterone administration is sufficient to increase LBM in trans men. Higher testosterone doses can lead to an earlier increase in muscle mass.

Inflammation as a Potential Mechanism Contributing to Sexual Functioning Following Initiation of Gender-Affirming Hormone Therapy

Inflammation as a Potential Mechanism Contributing to Sexual Functioning Following Initiation of Gender-Affirming Hormone Therapy

Increased rate of pancreatitis in gender diverse and transgender patients on hormone therapy: a case series study

BackgroundThere is limited data on the incidence of gastrointestinal-specific pathology in gender non-conforming (GNC) populations.MethodsRetrospective analysis of pancreatitis incidence rates in transgender and GNC persons exposed and not exposed to...

The Role of the Athletic Trainer in Providing Care to Transgender and Gender-Diverse Patients: Considerations for Medical Affirmation-Part II.

Recently, with discriminatory legislation efforts and changing participation policies in organized sports, media attention surrounding transgender and gender-diverse (TGD) individuals has increased. These changes and the historical lack of competence and education regarding the transgender patient population have resulted in subpar patient care and a misunderstanding of the athletic trainer's (AT's) role within the health care and compliance systems. This literature review is the second part of a 2-paper series, and our objective was to educate ATs on the processes relevant to medical affirmation, including compliance considerations regarding medical eligibility, and to establish the AT's role. The gender affirmation framework includes social and legal components, which are discussed in part 1 of this literature, and the medical component is thoroughly discussed in part 2. All health care providers involved in the care of TGD individuals should work collaboratively on an interprofessional care team and have a general knowledge of the gender-affirmation process, including gender-affirming hormone therapy, surgical options, known risks and complications, and the general health needs of TGD patients. With this knowledge, ATs, as point-of-care providers and members of the interprofessional care team, are uniquely positioned to help reduce health and health care disparities. Furthermore, ATs can use their knowledge to facilitate medical compliance and eligibility in the evolving policies of sporting organizations.

Disparities in Study Inclusion and Breast Cancer Screening Rates Among Transgender People: A Systematic Review

BackgroundBreast cancer screening trends of transgender and gender diverse (TGD) people remain largely unknown. This is concerning, as data are necessary to inform recommendations made by clinicians to their patients and by national guidelines to clinicians. The aim of this review is to explore the state of existing research literature and provide a summary report of current breast cancer screening rates in TGD adults. MethodsAll articles were identified using Medical Subject Headings terms. Inclusion criteria were all the following: (1) documents inclusion of at least one participant who identifies as a TGD person; (2) at least one TGD participant with top surgery or currently receiving estrogen-based gender-affirming hormone therapy; (3) results that report rates of breast cancer screening or mammogram referral. ResultsTwelve articles met inclusion criteria, six cross-sectional studies and six retrospective chart reviews. Three studies conducted secondary analysis of the Behavioral Risk Factor Surveillance System national dataset, and nine articles recruited their own sample with number of TGD participants ranging from 30 to 1,822 and number of cisgender women ranging from 242 to 18,275. Three studies found lower rates of screening in transfeminine persons receiving gender-affirming care compared with cisgender women; two studies found lower rates among TGD people compared with cisgender women; and three studies found no differences between the breast cancer screening rates of TGD and cisgender participants. ConclusionLimited studies recruit and report trends in breast cancer screening of TGD people. Those that do include TGD participants have mixed results, but overall TGD people had lower rates of breast cancer screening. More research is needed regarding breast cancer screening of TGD people to inform the development of protocols that ensure equitable access to preventative care.

Thyroid Cancer Prevalence, Risk Exposure, and Clinical Features Among Transgender Female Veterans.

Transgender women experience higher-than-average rates of multiple medical conditions. Thyroid cancer occurs more frequently in those assigned female at birth than in those assigned male at birth. We sought to characterize thyroid cancer among transgender female veterans. We reviewed charts of veterans who were (1) seen in Veterans Affairs clinics across the United States from July 2017 to December 2022, (2) had an International Classification of Diseases, revision 10, diagnosis code for thyroid cancer, and (3) had an International Classification of Diseases, revision 10, diagnosis code for gender dysphoria or were assigned male at birth and ever had a prescription for estrogens. Charts of cisgender veterans were also reviewed for comparison. Compared with calculated estimates of 0.641% (95% CI, 0.572-0.724) among cisgender females and 0.187% (95% CI, 0.156-0.219) among cisgender males, the measured prevalence among transgender female veterans was 0.341% (34/9988). Average age at thyroid cancer diagnosis in this population was 53.8 (± SEM 2.61) years. A total of 32.3% (11/34) of these patients had extrathyroidal disease at diagnosis. To our knowledge, this study represents the first report of thyroid cancer prevalence among transgender women in the United States. Risk exposure among all transgender veterans including further assessment of the possible contributions of obesity, smoking, and gender-affirming hormone therapy are important future analyses.

Gender-affirming hormone therapy preserves skeletal maturation in young mice via the gut microbiome.

Gender-affirming hormone therapy (GAHT) is often prescribed to transgender (TG) adolescents to alleviate gender dysphoria, but the effect of GAHT on the growing skeleton is unclear. We found GAHT to improve trabecular bone structure via increased bone formation in young male mice and not to affect trabecular structure in female mice. GAHT modified gut microbiome composition in both male and female mice. However, fecal microbiota transfers (FMTs) revealed that GAHT-shaped gut microbiome was a communicable regulator of bone structure and turnover in male, but not in female mice. Mediation analysis identified 2 species of Bacteroides as significant contributors to the skeletal effects of GAHT in male mice, with Bacteroides supplementation phenocopying the effects of GAHT on bone. Bacteroides have the capacity to expand Treg populations in the gut. Accordingly, GAHT expanded intestinal Tregs and stimulated their migration to the bone marrow (BM) in male but not in female mice. Attesting to the functional relevance of Tregs, pharmacological blockade of Treg expansion prevented GAHT-induced bone anabolism. In summary, in male mice GAHT stimulated bone formation and improved trabecular structure by promoting Treg expansion via a microbiome-mediated effect, while in female mice, GAHT neither improved nor impaired trabecular structure.

Bone Density in Transgender Youth on Gender-Affirming Hormone Therapy.

Some transgender youth are treated with gonadotropin-releasing hormone agonists (GnRHa) followed by testosterone or estradiol, which may impact bone mineral density (BMD). This cross-sectional study of transgender youth (n = 56, aged 10.4-19.8 years, 53% assigned female at birth [AFAB]) utilized total body dual-energy x-ray absorptiometry to evaluate BMD Z-scores, and associations between GnRHa duration, body mass index (BMI), and BMD. Participants on GnRHa alone (n = 19, 14 assigned male at birth [AMAB], 5 AFAB) at the time of the study visit were 13.8 [12.8, 15.3] (median [IQR]) years old, had been on GnRHa for 10 [5.5, 19.5] months, and began GnRHa at age 12 [10.4, 12.6] years. Total body BMD Z-score for individuals on GnRHa monotherapy was -0.10 [-0.8, 0.4] (AFAB, female norms) and -0.65 [-1.4, 0.22] (AMAB, male norms). AFAB participants (n = 21) on testosterone were age 16.7 [15.9, 17.8] years, had been on testosterone for 11 [7.3, 14.5] months, and started testosterone at age 16 [14.8, 16.8] years; total body BMD Z-score -0.2 [-0.5, 0] (male norms) and 0.4 [-0.2, 0.7] (female norms). AMAB participants (n = 16) were age 16.2 [15.1, 17.4] years, had been on estradiol for 11 [5.6, 13.7] months, and started estradiol at age 16 [14.4, 16.7] years; total body BMD Z-score -0.4 [-1.1, 0.3] (male norms) and -0.2 [-0.7, 0.6] (female norms). BMD Z-score was negatively correlated with GnRHa duration (male norms: r = -0.5, P = .005; female norms: r = -0.4, P = .029) and positively correlated with BMI (male norms: r = 0.4, P = .003; female norms: r = 0.4, P = .004). In this cross-sectional cohort, total body BMD Z-scores were slightly below average, but lowest in the AMAB group on GnRHa monotherapy.

Lactation induction in a transgender woman: case report and recommendations for clinical practice

BackgroundWe present a case of non-puerperal induced lactation in transgender woman. Medical literature on lactation induction for transgender women is scarce, and the majority of literature and protocols on lactation induction is based on research in cisgender women. Healthcare professionals may lack the precise knowledge about lactation induction and may therefore feel insecure when advice is requested. Subsequently, there is a rising demand for guidelines and support.MethodsPatient medical record was consulted and a semi-structured interview was conducted to explore the motive for lactation induction, the experience of lactation induction, and to gather additional information about the timeline and course of events.Case presentationIn this case a 37-year-old transgender woman, who was under the care of the centre of expertise on gender dysphoria in Amsterdam, and in 2020 started lactation induction because she had the wish to breastfeed her future infant. She was in a relationship with a cisgender woman and had been using gender affirming hormone therapy for 13 years. Prior to initiating gender affirming hormone therapy she had cryopreserved her semen. Her partner conceived through Intracytoplasmic Sperm Injection, using our patient’s cryopreserved sperm.To induce lactation, we implemented a hormone-regimen to mimic pregnancy, using estradiol and progesterone, and a galactogogue; domperidone. Our patient started pumping during treatment. Dosage of progesterone and estradiol were significantly decreased approximately one month before childbirth to mimic delivery and pumping was increased. Our patient started lactating and although the production of milk was low, it was sufficient for supplementary feeding and a positive experience for our patient.Two weeks after birth, lactation induction was discontinued due to suckling problems of the infant and low milk production.ConclusionsThis case report underlined that lactation induction protocols commonly used for cisgender women are also effective in transgender women. However, the amount of milk produced may not be sufficient for exclusive nursing. Nevertheless, success of induced lactation may be attributed to its importance for parent-infant bonding, rather than the possibility of exclusive chestfeeding.

Clinically Relevant Laboratory Monitoring of Gender-Affirming Hormone Therapy in Transgender People-Experiences from a Teaching Hospital in the Netherlands.

Transgender care is shifting from academic to nonacademic settings leading to use of common (immunoassay) compared to sophisticated (mass spectrometry) methods to monitor estradiol and testosterone during gender-affirming hormone therapy (GAHT). The type of assay can influence results and have significant implications for clinical decision making. An evidence gap is present in recommendations regarding the assay needed to monitor GAHT. The present study aimed to summarize current evidence and evaluate immunoassay estradiol and testosterone concentrations in transgender people visiting a nonacademic hospital for GAHT. Clinical practice guidelines on GAHT and scientific literature on assay methodologies were screened and summarized. Laboratory and medical data from 252 patients who visited the transgender outpatient clinic of the Maasstad Hospital for GAHT between 2020 and 2022 were retrospectively analyzed. Our research showed that the most used clinical practice guidelines for GAHT provide hormonal target values without recommending a preferred method. A comprehensive literature search on agreement between immunoassay and mass spectrometry showed substantial heterogeneity in results. Retrospective analysis of our immunoassay measured data in transgender people showed hormonal changes during GAHT that are to be expected from the medication used. We demonstrate that laboratory monitoring of GAHT in a nonacademic hospital can be done safely by immunoassay in most cases. Only in cases where clinical observation is discordant with the hormonal results do more sophisticated methods need to be deployed. A best practice model was proposed for transgender care in nonacademic hospitals.

Clinical and sociodemographic characteristics as predictors for quality of life in transmasculine and transfeminine individuals receiving gender-affirming hormone therapy

Healthcare systems and providers have increasingly acknowledged the role and impact of social determinants in overall health. However, gender-diverse individuals face persistent health disparities due to their identities. There is limited research on the impact of clinical and sociodemographic characteristics on mood and quality of life (QoL) for transgender (TG) individuals. Our study aims to understand and better elucidate social and clinical characteristics of transmasculine (TM) and transfeminine (TF) individuals and their impact on quality of life and depressive symptoms. In this cross-sectional study, 298 TF and TM individuals on gender-affirming hormone therapy (GAHT) were surveyed about their demographic characteristics (age, gender identity, body mass index (BMI), and education), social needs, mood, and quality of life. Multivariable regression modelling was performed to assess the effect of each variable listed above on three domains of QoL (psychological, environmental, and physical) as well as depressive symptoms. We find that QoL scores are similar between TM and TF individuals, with scores in the psychological domain particularly low in both cohorts. TM individuals report higher rates of stress and restroom avoidance than TF individuals. In particular, psychological well-being (measured by the psychological domain of QoL and depressive symptoms) is significantly associated with increased BMI, financial instability, and stress in TM individuals while for TF individuals, psychological well-being is associated with stress and social integration. These data suggest that social circumstances are key drivers of QoL and psychological well-being among gender-diverse individuals receiving GAHT with specific differences between TF and TM individuals. This information may be utilized by healthcare providers and policymakers to address and improve clinical care and social policies to improve health equity for gender-diverse individuals.

A Holistic Framework for the Evaluation of Kidney Function in a Gender-Diverse Landscape

The most commonly used equations to estimate glomerular filtration rate incorporate a binary male-female sex coefficient, which has important implications for the care of transgender, gender-diverse, and nonbinary (TGD) people. Whether "sex assigned at birth" or a binary "gender identity" is most appropriate for the computation of estimated glomerular filtration rate (eGFR) is unknown. Furthermore, the use of gender-affirming hormone therapy (GAHT) for the development of physical changes to align TGD people with their affirmed gender is increasingly common, and may result in changes in serum creatinine and cystatin C, the biomarkers commonly used to estimate glomerular filtration rate. The paucity of current literature evaluating chronic kidney disease (CKD) prevalence and outcomes in TGD individuals on GAHT makes it difficult to assess any effects of GAHT on kidney function. Whether alterations in serum creatinine reflect changes in glomerular filtration rate or simply changes in muscle mass is unknown. Therefore, we propose a holistic framework to evaluate kidney function in TGD people. The framework focuses on kidney disease prevalence, risk factors, sex hormones, eGFR, other kidney function assessment tools, and the mitigation of health inequities in TGD people.

Effects of gender affirming hormone therapy with testosterone on coagulation and hematological parameters in transgender people assigned female at birth: A systematic review and meta-analysis

BackgroundHormone replacement therapy is associated with an increased thromboembolic risk. The effects of testosterone (T) on coagulation markers in people assigned female at birth (AFAB) under gender affirming hormone therapy (GAHT) are not well described. MethodsSystematic review and meta-analysis on English-language articles retrieved from PubMed, Scopus and Cochrane Library up to April 2023 investigating T therapy in AFAB people. Coagulation parameters included international normalized ratio (INR), fibrinogen, activated partial thromboplastin clotting time (aPTT), plasminogen activator inhibitor-1 (PAI-1); hematological variables included hemoglobin (Hb) and hematocrit (HCT). We also reported the rate of thromboembolic events. Data were combined as mean differences (MD) with a 95 % confidence interval (CI) of pre- vs post-follow-up values, using random-effects models. ResultsWe included 7 studies (6 prospective and 1 retrospective) providing information on 312 subjects (mean age: 23 to 30 years) who underwent GAHT with variable T preparation. T therapy was associated with a significant increase in INR values [MD: 0.02, 95 % confidence interval (CI): 0.01–0.03; p = 0.0001], with negligible heterogeneity (I2 = 4 %). T therapy was associated with increased Hb (MD: 1.48 g/dL, 95%CI: 1.17 to 1.78; I2 = 9 %) and HCT (4.39 %, 95%CI: 3.52 to 5.26; I2 = 23 %) values. No effect on fibrinogen, aPTT and PAI-1 was found. None of the study reported thromboembolic events during the follow-up. ConclusionTherapy with T increased blood viscosity in AFAB men. A slight increase in INR values was also found, but the clinical relevance and mechanism(s) of this finding needs to be clarified.

(043) Gender-Affirming Bilateral Orchiectomy Prior to Vaginoplasty versus with Vaginoplasty: A Comparison of Preoperative Goals and Postoperative Satisfaction

Abstract Introduction Gender-affirming bilateral orchiectomy (GA-BO), defined here as either a standalone procedure and/or precursor to vaginoplasty, is associated with a decrease in gender-affirming hormone therapy (GAHT) dosages. In comparison to bilateral orchiectomy at time of gender-affirming vaginoplasty (GA-V), GA-BO is associated with shorter waitlist times, procedure duration, and outpatient recovery. While objective benefits of GA-BO have been described, there is limited qualitative data that assesses the preoperative goals and postoperative satisfaction of patients who elect GA-BO. We aim to assess the decision-guiding factors that led patients to select GA-BO, and to compare measures of patient satisfaction between GA-BO and GA-V patients. Objective To assess the decision-guiding factors that led patients to select gender-affirming bilateral orchiectomy before vaginoplasty versus with vaginoplasty, and to compare measures of patient satisfaction between groups. Methods A retrospective chart review identified 170 patients who underwent GA-BO (n=106; 64%) or GA-V (n=64; 36%) between 4/2017 and 12/2020 at our institution. Patients were emailed a link to an anonymous, online questionnaire (QualtricsTM). Results 136/170 (80%) patients completed the questionnaire: 86/136 (63%) respondents were GA-BO patients and 50/136 GA-V (37%). 78/86 (91%) of GA-BO respondents had either subsequently undergone vaginoplasty, or, planned to do so in the future. For patients who later underwent vaginoplasty, the mean reported time interval between GA-BO and vaginoplasty was 15 months [Range: 1–34 months]. Respondents prioritized the following expectations in their decision to undergo GA-BO: potential to decrease GAHT medications and dosages (reported as important by 67%), low rates of complications (56.5%), short recovery time (51.6%), and low postoperative pain (46.2%). GA-BO and GA-V patients reported high postoperative improvement in various indices of gender dysphoria and body image, with only 1/4 indices of gender dysphoria differing significantly between the two groups (Figure 1). Unsurprisingly, GA-V patients reported a significantly greater improvement in 3/3 body image indices. Conclusions GA-BO is a low-risk procedure that provides a more immediate option to decrease gender dysphoria and improve QOL. All patients who were assigned male at birth and are interested in genital gender-affirming surgery should be made aware of the advantages of GA-BO and offered GA-BO alongside GA-V. Disclosure No.

(001) Brain Activation Patterns Associated with Visually Evoked Sexual Arousal in Female-To-Male Transgender Individuals

Abstract Introduction Cross-sex hormones in female-to-male (FtM) transgender individuals play a crucial role in brain plasticity. Brain activity associated with sexual arousal in FtM transgenders receiving cross-sex hormones is poorly understood. Objective This study aimed to compare brain activation patterns associated with sexual arousal between FtM transgenders and premenopausal women using a 3.0 Tesla functional magnetic resonance imaging (fMRI). Methods This study included 13 FtM transgenders (mean age: 43.2±6.4 years) and 13 premenopausal women (mean age: 41.5 ± 8.3 years). The FtM transgender individuals, who have had sex-reassignment surgery, received testosterone supplementary therapy. Sexual orientation was evaluated using the Kinsey sexuality rating scale (0 = exclusively heterosexual; 6 = exclusively homosexual). Serum sex hormones were measured, including free testosterone (free-T), estradiol (E2), follicle-stimulating, and luteinizing hormones. Visual sexual stimulation began with a 30-s cross fixation (rest condition), followed by a 30-s natural documentary (neutral condition), 540-s erotic video (sexual activation condition), then a 30-s cross fixation (rest condition). The fMRI data were post-processed using SPM8 software. Results The average rating of the Kinsey scale in the FtM transgenders was 5.6 ± 0.5, indicating their sexual orientation falls within the category of homosexual. The FtM transgenders showed significant increases in the free-T levels (18.8±18.9 pg/mL vs. 0.4±0.4 pg/mL, p &amp;lt; 0.001) and significant decreases in the E2 levels (45.4±32.0 pg/mL vs. 279.2±247.3 pg/mL, p = 0.001) compared with premenopausal women. The brain areas with significantly higher activities during visual sexual stimuli in the FtM transgenders compared with premenopausal women included the superior parietal lobule, middle occipital gyrus, and superior frontal gyrus (p &amp;lt; 0.001). Conclusions This study illustrates the specific brain activation patterns associated with sexual arousal in female-to-male (FtM) transgenders. These findings could contribute to our understanding of the neural mechanisms associated with sexual arousal in relation to the levels of sexual hormones in FtM transgenders. This research was supported by grants from the National Research Foundation funded by the government (MSIT; 2022R1A2C2007809, 2021R1C1C2011748). Disclosure No.