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Introduction Excess visceral fat increases the risk of type 2 diabetes and cardiovascular disease and is influenced by sex hormones. Our aim was to investigate changes in visceral fat and the ratio of visceral fat to total body fat (VAT/TBF) and their associations with changes in lipids and insulin resistance after 1 year of hormone therapy in trans persons. Methods In 179 trans women and 162 trans men, changes in total body and visceral fat estimated with dual-energy X-ray absorptiometry before and after 1 year of hormone therapy were related to lipids and insulin resistance [homeostatic model assessment of insulin resistance (HOMA-IR)] with linear regression analysis. Results In trans women, total body fat increased by 4.0 kg (95% CI 3.4, 4.7), while the amount of visceral fat did not change (−2 grams; 95% CI −15, 11), albeit with a large range from −318 to 281, resulting in a decrease in the VAT/TBF ratio of 17% (95% CI 15, 19). In trans men, total body fat decreased with 2.8 kg (95% CI 2.2, 3.5), while the amount of visceral fat did not change (3 g; 95% CI −10, 16; range −372, 311), increasing the VAT/TBF ratio by 14% (95% CI 10, 17). In both groups, VAT/TBF was not associated with changes in blood lipids or HOMA-IR. Conclusions Hormone therapy in trans women and trans men resulted in changes in VAT/TBF, mainly due to changes in total body fat and were unrelated to changes in cardiometabolic risk factors, which suggests that any unfavorable cardiometabolic effects of hormone therapy are not mediated by changes in visceral fat or VAT/TBF.

Objective Sex steroid hormones like estrogens have a key role in the regulation of energy homeostasis and metabolism. In transwomen, gender-affirming hormone therapy like estradiol (in combination with antiandrogenic compounds) could affect metabolism as well. Given that the underlying pathophysiological mechanisms are not fully understood, this study assessed circulating estradiol-driven microRNAs (miRs) in transwomen and their regulation of genes involved in metabolism in mice. Methods Following plasma miR-sequencing (seq) in a transwomen discovery (n = 20) and validation cohort (n = 30), we identified miR-224 and miR-452. Subsequent systemic silencing of these miRs in male C57Bl/6 J mice (n = 10) was followed by RNA-seq-based gene expression analysis of brown and white adipose tissue in conjunction with mechanistic studies in cultured adipocytes. Results Estradiol in transwomen lowered plasma miR-224 and -452 carried in extracellular vesicles (EVs) while their systemic silencing in mice and cultured adipocytes increased lipogenesis (white adipose) but reduced glucose uptake and mitochondrial respiration (brown adipose). In white and brown adipose tissue, differentially expressed (miR target) genes are associated with lipogenesis (white adipose) and mitochondrial respiration and glucose uptake (brown adipose). Conclusion This study identified an estradiol-drive post-transcriptional network that could potentially offer a mechanistic understanding of metabolism following gender-affirming estradiol therapy.

Objective Gender-affirming hormonal treatment (HT) in trans people changes physical appearance. Muscle mass and strength are important aspects of physical appearance, but few data exist on the effect of HT on grip strength and muscle mass. This study aimed to investigate the change in grip strength in trans people during the first year of HT and to study the possible determinants of this change and the associations between changes in grip strength, lean body mass and bone mineral density (BMD). Design and methods A multicenter, prospective study was performed, including 249 transwomen and 278 transmen. Grip strength, lean body mass and BMD were measured at baseline and after 1 year. Results After 1 year of HT, grip strength decreased with −1.8 kg (95% CI −2.6; −1.0) in transwomen and increased with +6.1 kg (95% CI +5.5; +6.7) in transmen. No differences in grip strength change was found between age groups, BMI groups, hormonal administration routes or hormone concentrations. In transmen, increase in grip strength was associated with increase in lean body mass (per kg increase in grip strength: +0.010 kg, 95% CI +0.003; +0.017), while this was not found in transwomen (per kg increase in grip strength: +0.004 kg, 95% CI −0.000; +0.009). Change in grip strength was not associated with change in BMD in transwomen and transmen. Conclusions After 1 year of HT, grip strength decreased in transwomen, and increased in transmen. In transmen only, change in grip strength was associated with change in lean body mass.

Context: The impact of gender-affirming hormone therapy (HT) on cardiometabolic parameters is largely unknown. Objective: The effects of 1 year of treatment with oral or transdermal administration of estrogen (plus cyproterone) and transdermal or IM application of testosterone on serum lipid levels and blood pressure (BP) were assessed in transgender persons. Design and Methods: In this prospective, observational substudy of the European Network for the Investigation of Gender Incongruence, measurements were performed before and after 12 months of HT in 242 transwomen and 188 transmen from 2010 to 2017. Results: Mean values are reported. In transmen, HT increased diastolic BP (2.5%; 95% CI, 0.6 to 4.4) and levels of total cholesterol (TC; 4.1%; 95% CI, 1.5 to 6.6), low-density lipoprotein-cholesterol (LDL-C; 13.0%; 95% CI, 9.2 to 16.8), and triglycerides (36.9%; 95% CI, 29.8 to 44.1); high-density lipoprotein-cholesterol levels decreased (HDL-C; 10.8%; 95% CI, 214.0 to 27.6). In transwomen, HT slightly decreased BP (systolic BP, 22.6%, 95% CI, 24.2 to 21.0; diastolic BP, 22.2%, 95% CI, 24.0 to 20.4) and decreased levels of TC (29.7%; 95% CI, 211.3 to 28.1), LDL-C (26.0%; 95% CI, 28.6 to 3.6), HDL-C (29.3%; 95% CI, 211.4 to 27.3), and triglycerides (210.2%; 95% CI, 214.5 to 25.9). Conclusion: Unfavorable changes in lipid profile were observed in transmen; a favorable effect was noted in transwomen. HT effects on BP were negligible. Long-term studies are warranted to assess whether and to what extent HT in trans individuals results in a differential effect on cardiovascular disease outcomes.

BACKGROUND AND OBJECTIVES: The effects of endocrinological treatment on cardiovascular risk profile in transgender adolescents are unknown. In this retrospective cohort study, we aim to investigate these effects and assess obesity and dyslipidemia prevalence in transgender adolescents at 22 years compared with peers. METHODS: Changes in BMI, systolic blood pressure (SBP), diastolic blood pressure (DBP), glucose, homeostatic model assessment for insulin resistance (HOMA-IR), and lipid values during treatment, along with the prevalence of obesity and dyslipidemia at 22 years, were recorded in 71 transwomen and 121 transmen who started gonadotropin-releasing hormone agonists in their adolescence (15 years), with a subsequent addition of sex hormones (17 years). RESULTS: In transwomen, changes in BMI (+3.0; 95% confidence interval [CI] 1.6 to 4.4), SBP (−2 mm Hg; 95% CI −7 to 3), DBP (+10 mm Hg; 95% CI 7 to 14), glucose (0.0 mmol/L; 95% CI −0.2 to 0.2), HOMA-IR (+0.6; 95% CI −0.6 to 1.9), and lipid values were similar or more favorable compared with peers. The same was true for transmen regarding changes in BMI (+2.3; 95% CI 1.7 to 2.9), SBP (+7 mm Hg; 95% CI 3 to 10), DBP (+7 mm Hg; 95% CI 5 to 10), glucose (+0.1 mmol/L; 95% CI −0.1 to 0.3), HOMA-IR (−0.2; 95% CI −0.8 to 0.3), and lipid values. At age 22, obesity prevalence was 9.9% in transwomen, 6.6% in transmen, 2.2% in ciswomen, and 3.0% in cismen. CONCLUSIONS: Generally, endocrinological treatment in transgender adolescents is safe regarding cardiovascular risk. Because obesity is more prevalent in transgender adolescents compared with peers, body weight management should be important during the medical trajectory.

© 2018 American Society of Andrology and European Academy of Andrology. In trans persons on gender-affirming hormonal treatment, a decrease (in trans women) or increase (in trans men) in hematocrit is often observed. Reference ranges for evaluation of hematocrit levels in trans persons have not been established. This prospective cohort study is part of the European Network for the Investigation of Gender Incongruence (ENIGI). At the Ghent and Amsterdam sites, we included 625 hormone-naive trans persons. Gender-affirming hormonal treatment was initiated at the first visit. In trans men, serum hematocrit (Hct) levels increased during the first year (+4.9 Hct %, 95% CI 3.82-5.25), with the most pronounced increase during the first 3 months (+2.7 Hct %, 95% CI 1.94-3.29). Trans men receiving testosterone esters had a larger increase in serum hematocrit levels compared to trans men receiving testosterone undecanoate (Δ 0.8 Hct %). Of 192 trans men, 22 (11.5%) developed serum hematocrit levels ≥50.0%. Trans men on testosterone undecanoate were less likely to develop hematocrit levels ≥50% or ≥52%, compared to trans men on testosterone esters, and were less likely to develop hematocrit levels ≥50%, compared to trans men on testosterone gel. In trans women, serum hematocrit had dropped by 4.1 Hct % (95% CI 3.50-4.37) after 3 months, after which only small decreases were observed. In conclusion, serum hematocrit levels can be found in the reference range of the perceived gender as from 3 months after the initiation of gender-affirming hormonal treatment.

Background Transgender adolescents aspiring to have the body characteristics of the affirmed sex can receive hormonal treatment. However, it is unknown how body shape and composition develop during treatment and whether transgender persons obtain the desired body phenotype. Aim To examine the change in body shape and composition from the start of treatment with gonadotropin-releasing hormone agonists (GnRHa) until 22 years of age and to compare these measurements at 22 years with those of age-matched peers. Methods 71 transwomen (birth-assigned boys) and 121 transmen (birth-assigned girls) who started treatment from 1998 through 2014 were included in this retrospective study. GnRHa treatment was started and cross-sex hormonal treatment was added at 16 years of age. Anthropometric and whole-body dual-energy x-ray absorptiometry data were retrieved from medical records. Linear mixed model regression was performed to examine changes over time. SD scores (SDS) were calculated to compare body shape and composition with those of age-matched peers. Outcomes Change in waist-hip ratio (WHR), total body fat (TBF), and total lean body mass (LBM) during hormonal treatment. SDS of measures of body shape and composition compared with age-matched peers at 22 years of age. Results In transwomen, TBF increased (+10%, 95% CI = 7–11) while total LBM (−10%, 95% CI = −11 to −7) and WHR (−0.04, 95% CI = −0.05 to −0.02) decreased. Compared with ciswomen, SDS at 22 years of age were +0.3 (95% CI = 0.0–0.5) for WHR, and 0.0 (95% CI = −0.2 to 0.3) for TBF. Compared with cismen, SDS were −1.0 (95% CI = −1.3 to −0.7) for WHR, and +2.2 (95% CI = 2.2–2.4) for TBF. In transmen, TBF decreased (−3%, 95% CI = −4 to −1), while LBM (+3%, 95% CI = 1–4) and WHR (+0.03, 95% CI = 0.01–0.04) increased. Compared with ciswomen, SDS at 22 years of age were +0.6 (95% CI = 0.4–0.8) for WHR, and −1.1 (95% CI = −1.4 to −0.9) for TBF. Compared with cismen, SDS were −0.5 (95% CI = −0.8 to −0.3) for WHR, and +1.8 (95% CI = 1.6–1.9) for TBF. Clinical Implications Knowing body shape and composition outcomes at 22 years of age will help care providers in counseling transgender youth on expectations of attaining the desired body phenotype. Strengths and Limitations This study presents the largest group of transgender adults to date who started treatment in their teens. Despite missing data, selection bias was not found. Conclusions During treatment, WHR and body composition changed toward the affirmed sex. At 22 years of age, transwomen compared better to age-matched ciswomen than to cismen, whereas transmen were between reference values for ciswomen and cismen.

Objective Cross-sex hormonal therapy (CHT) in trans persons affects their total body fat and total lean body mass. However, it is unknown how separate body regions are affected and whether these changes alter body shape. Therefore, the aim of this study was to determine the effects on body fat and lean body mass in separate body regions and on body shape after one year of CHT. Design and methods In a multicenter prospective study at university hospitals, 179 male-to-female gender dysphoric persons, referred to as transwomen, and 162 female-to-male gender dysphoric persons, referred to as transmen, were included. All underwent whole-body dual-energy X-ray absorptiometry and anthropometric measurements before and after one year of CHT. Results In transwomen, increases in body fat ranged from +18% (95% CI: 13%;23%) in the android region to +42% (95% CI: 37%;46%) in the leg region and +34% (95% CI: 29%;38%) in the gynoid region. In transmen, changes in body fat ranged from −16% (95% CI: −19;−14%) in the leg region and −14% in the gynoid region (95% CI: −16%;−12) to no change in the android region (+1%, 95% CI: −3%;5%). Waist-to-hip ratio (WHR) decreased in transwomen (−0.03, 95% CI: −0.04;−0.02) mainly due to an increase in hip circumference (+3.2 cm, 95% CI: 2.3;4.0). Transmen have a decrease in hip circumference (−1.9 cm, 95% CI: −3.1;−0.7) resulting in an increase in WHR (+0.01, 95% CI: 0.00;0.02). Conclusions CHT causes a more feminine body fat distribution and a lower WHR in transwomen and a more masculine body fat distribution with a lower hip circumference in transmen.

Context: Breast development is a key feature of feminization and therefore important to transwomen (male-to-female transgender persons). However, it is not exactly known when breast development starts after initiating cross-sex hormone therapy (CHT) and how much growth may be expected of CHT alone. Objective: To investigate breast development in centimeters and bra cup-sizes in transwomen during their first year of CHT, and whether clinical or laboratory parameters predict the breast development. Design: This study was performed as part of the European Network for the Investigation of Gender Incongruence (ENIGI), which is a prospective multicenter cohort study. Setting: Specialized gender clinics in Amsterdam, Ghent, and Florence. Participants: All transwomen who completed the first year of CHT (n=229) were eligible for analyses. Intervention: Cross-sex hormone therapy. Main outcome measures: Breast development in centimeter and cup-size. Results: The median age of the included transwomen was 28 years (range 18;69 years). Mean breast - chest difference increased from 4.1±2.9cm at baseline to 7.9±3.1cm after one year of CHT, mainly resulting in less than an AAA cup-size (48.7%). Main breast development occurred in the first six months of therapy. Serum estradiol levels did not predict breast development after one year CHT (first quartile: +3.6cm(95% CI +2.7;+4.5cm), second quartile: +3.2cm(95% CI +2.3;+4.2cm), third quartile: +4.4(95% CI +3.5;+5.3cm), fourth quartile: +3.6cm(95% CI +2.7;+4.5cm)). Conclusion: This study shows that after one year of CHT breast development is modest and occurs primarily in the first six months. No clinical or laboratory parameters were found that predict breast development.

Sex steroids are important determinants of bone acquisition and bone homeostasis. Cross-sex hormonal treatment (CHT) in transgender persons can affect bone mineral density (BMD). The aim of this study was to investigate in a prospective observational multicenter study the first-year effects of CHT on BMD in transgender persons. A total of 231 transwomen and 199 transmen were included who completed the first year of CHT. Transwomen were treated with cyproterone acetate and oral or transdermal estradiol; transmen received transdermal or intramuscular testosterone. A dual-energy X-ray absorptiometry (DXA) was performed to measure lumbar spine (LS), total hip (TH), and femoral neck (FN) BMD before and after 1 year of CHT. In transwomen, an increase in LS (+3.67%, 95% confidence interval [CI] 3.20 to 4.13%, p < 0.001), TH (+0.97%, 95% CI 0.62 to 1.31%, p < 0.001), and FN (+1.86%, 95% CI 1.41 to 2.31%, p < 0.001) BMD was found. In transmen, TH BMD increased after 1 year of CHT (+1.04%, 95% CI 0.64 to 1.44%, p < 0.001). No changes were observed in FN BMD (-0.46%, 95% CI -1.07 to 0.16%, p = 0.144). The increase in LS BMD was larger in transmen aged ≥50 years (+4.32%, 95% CI 2.28 to 6.36%, p = 0.001) compared with transmen aged

The cause of prolactin alterations in transgender persons is often assigned to oestrogens, but the precise cause and time course during different phases of cross-sex hormone treatment (CHT) remain unclear. In this study, we prospectively examined prolactin levels in 55 female-to-males (FtMs) and 61 male-to-females (MtFs) during the first year of CHT. Because long-term prolactin data were not available in this population, we studied these levels in a retrospective population of 25 FtMs and 38 MtFs who underwent gonadectomy. FtMs were treated with testosterone and MtFs with estradiol, with or without the anti-androgen cyproterone acetate (CPA) (after gonadectomy CPA is cessated). During the first year of CHT, prolactin decreased with 25% (95CI: −33%, −12%) in FtMs and increased with 193% (95CI: 156%, 219%) in MtFs. Eighteen MtFs developed hyperprolactinemia (≥0.6 IU L−1). In the retrospective population, post-gonadectomy levels in FtMs were lower than baseline levels (−39%; 95CI: −51%, −20%) while in MtFs post-gonadectomy levels and baseline levels were comparable (−6%; 95CI: −24%, 15%). No hyperprolactinemia was found after gonadectomy. In conclusion, in FtMs, prolactin decreased consistently during CHT and in MtFs, prolactin increased during pre-surgical CHT but normalised after gonadectomy. It is likely that CPA induces increasing prolactin levels in MtFs.

Summary Weight gain and body fat increase the risk of cardiometabolic disease. Cross-sex hormone therapy in transgender persons leads to changes in body weight and body composition, but it is unclear to what extent. We performed a meta-analysis to investigate the changes in body weight, body fat and lean body mass during cross-sex hormone therapy in transgender persons. We searched the PubMed database for eligible studies until November 2015. Ten studies reporting changes in body weight, body fat or lean mass in hormone naive transgender persons were included, examining 171 male-to-female and 354 female-to-male transgender people. Pooled effect estimates in the male-to-female group were +1.8 kg (95% CI: 0.2;3.4) for body weight, +3.0 kg (2.0;3.9) for body fat and −2.4 kg (−2.8; −2.1) for lean body mass. In the female-to-male group, body weight changed with +1.7 kg (0.7;2.7), body fat with −2.6 kg (−3.9; −1.4) and lean body mass with +3.9 kg (3.2;4.5). Cross-sex hormone therapy increases body weight in both sexes. In the male-to-female group, a gain in body fat and a decline in lean body mass are observed, while the opposite effects are seen in the female-to-male group. Possibly, these changes increase the risk of cardiometabolic disease in the male-to-female group.

Introduction Cross-sex hormone therapy is an essential part of gender affirming treatment of transgender individuals. Studies systematically describing the physical and psychological effects of hormonal treatment of transgender persons are scarce. Aim The aim of the current protocol is to evaluate clinical and side-effects of cross-sex hormonal treatment in trans persons. Methods The European Network for the Investigation of Gender Incongruence (ENIGI) is a multicenter prospective study. Because of the relatively low prevalence of the condition and small number of specialized centers, international collaboration is warranted. Four European treatment centers, Ghent, Oslo, Florence, and Amsterdam, developed a common study and treatment protocol. Main Outcome Measures Outcome measures include hormonal and metabolic parameters, bone density, secondary sex and anthropometric characteristics, and physical and psychological well-being. Results Thus far, 333 trans women and 343 trans men have been included in the ENIGI Endocrine protocol. The study is still ongoing. Conclusion In recent years, the number of trans persons seeking gender affirming treatment has increased. However, well-designed prospective studies evaluating safety and effectiveness of current hormonal treatment protocols are lacking. Therefore we started the ENIGI collaboration. In this article we give a detailed description of the study protocol, objectives, and design of the ENIGI Endocrine protocol.