Literature on the efficacy and safety of gender-affirming hormonal treatment (GAHT) in transgender people is limited. For this reason, in 2010 the European Network for the Investigation of Gender Incongruence (ENIGI) study was born. The aim of this review is to summarize evidence emerging from this prospective multicentric study and to identify future perspectives. GAHT was effective in inducing desired body changes in both trans AMAB and AFAB people (assigned male and female at birth, respectively). Evidence from the ENIGI study confirmed the overall safety of GAHT in the short/mid-term. In trans AMAB people, an increase in prolactin levels was demonstrated, whereas the most common side effects in trans AFAB people were acne development, erythrocytosis, and unfavorable changes in lipid profile. The main future perspectives should include the evaluation of the efficacy and safety of non-standardized hormonal treatment in non-binary trans people. Furthermore, long-term safety data on mortality rates, oncological risk, and cardiovascular, cerebrovascular and thromboembolic events are lacking. With this aim, we decided to extend the observation of the ENIGI study to 10 years in order to study all these aspects in depth and to answer these questions.

Background: Gender minority individuals, on average, experience higher rates of mental health problems. Mounting work suggests that gender minority stress (GMS) contributes to mental health outcomes in transgender/gender-nonconforming individuals. Aim: We assessed whether GMS decreased in transgender people after initiating gender-affirming hormone therapy (GAHT), and we identified social predictors and hormonal associations for GMS at 2 time points. Methods: GMS was surveyed through self-report questionnaires tapping into proximal and distal stressors and coping constructs following the minority stress framework. Eighty-five transgender persons wishing to undertake hormonal interventions were assessed prospectively at start of GAHT and after 7.7 ± 3.5 months (mean ± SD). Sixty-five cisgender persons served as a control group. Outcomes: (1) Proximal stressors were surveyed by the Beck Depression Inventory II, State-Trait Anxiety Inventory, Scale for Suicide Ideation, Suicidal Thoughts/Attempts, Stigma Consciousness Questionnaire, and Perceived Stress Scale; (2) distal stressors by the Everyday Discrimination Scale; and (3) coping constructs by the Resilience Scale, social network, social standing, and Marlowe Crowne Social Desirability Scale. Results: Transgender people experienced higher rates of proximal stressors (Beck Depression Inventory II, State-Trait Anxiety Inventory, Scale for Suicide Ideation, Suicidal Thoughts/Attempts, Perceived Stress Scale) and had lower protective factors (social standing) prior to and during GAHT than cisgender people. Social network and resilience were lower in transgender people relative to cisgender peers only at baseline. Prospectively, decreasing trait anxiety was observed in transgender people. Social factors were adequate predictors of multiple GMS constructs. Specifically, a major role for social network emerged. As for hormonal associations, only serum estradiol levels in transgender women with GAHT were negatively associated with trait anxiety and suicidal thoughts/attempts but positively with resilience and social desirability. Clinical Implications: Stimulating a social environment supportive of diverse identities, particularly by investing in social networks as a resource for resilience, is likely to alleviate GMS. Strengths and Limitations: Longer duration of interventions with sex steroid treatment, with continued resilience-enhancing strategies, is needed to observe further alleviation of GMS in transgender persons. Also, objective and subjective GMS identification with heteronormative attitudes and beliefs should be surveyed for good measure when assessing GMS. Conclusion: Transgender people experienced more GMS throughout study visits than cisgender people did. With a relatively short period of GAHT, some significant changes in and predictors for experienced GMS emerged.

Background Initiating feminizing gender-affirming hormone therapy (GAHT) in transgender women causes a steep decline in serum testosterone. It is unknown if testosterone concentrations change further and whether adrenal androgen levels change during feminizing GAHT and after gonadectomy. This limits clinical decision making in transgender women with symptoms attributed to GAHT or gonadectomy. Methods Transgender women (n = 275) initiating estradiol and cyproterone acetate (CPA) were included at baseline, and had follow-up visits after 3 months, 12 months, and 2 to 4 years. During follow-up, 49.5% of transgender women underwent a gonadectomy. Total testosterone (TT), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), and androstenedione (A4) were measured using liquid chromatography tandem mass spectrometry. Results After 3 months of GAHT, mean TT, calculated free testosterone (cFT), and A4 decreased by 18.4 nmol/L (95% CI, −19.4 to −17.4, P < 0.001 [ie, −97.1%]), 383 pmol/L (95% CI, −405 to −362, P < 0.001 [ie, −98.3%]), and 1.2 nmol/L (95% CI, −1.4 to −1.0, P < 0.001 [ie, −36.5%]), respectively, and remained stable thereafter. DHEA and DHEAS decreased by 7.4 nmol/L (95% CI, −9.7 to −5.1 [ie, −28.0%]) and 1.8 µmol/L (95% CI, −2.2 to −1.4 [ie, −20.1%]), respectively, after 1 year and did not change thereafter. After gonadectomy, CPA therapy is stopped, which induced no further change in TT, cFT, DHEA, DHEAS, and A4 compared with those who did not undergo gonadectomy. Conclusions Our findings confirm that after an initial drop, testosterone levels in transgender women remain stable. Adrenal androgens decrease in the first year of CPA and estrogen supplementation and remain unchanged after gonadectomy. Androgens did not change after gonadectomy and cessation of CPA. Correlates with clinical symptoms remain to be elucidated.

Much research has been conducted on sexual differences of the human brain to determine whether and to what extent a brain gender exists. Consequently, a variety of studies using different neuroimaging techniques attempted to identify the existence of a brain phenotype in people with gender dysphoria (GD). However, to date, brain sexual differences at the metabolite level using magnetic resonance spectroscopy (¹H-MRS) have not been explored in transgender people. In this study, 28 cisgender men (CM) and 34 cisgender women (CW) and 29 transgender men with GD (TMGD) underwent ¹H-MRS at 3 Tesla MRI to characterize common brain metabolites. Specifically, levels of N–acetyl aspartate (NAA), choline (Cho), creatine (Cr), glutamate and glutamine (Glx), and myo-inositol + glycine (mI + Gly) were assessed in two brain regions, the amygdala-anterior hippocampus and the lateral parietal cortex. The results indicated a sex-assigned at birth pattern for Cho/Cr in the amygdala of TMGD. In the parietal cortex, a sex-assigned at birth and an intermediate pattern were found. Though assessed post-hoc, exploration of the age of onset of GD in TMGD demonstrated within-group differences in absolute NAA and relative Cho/Cr levels, suggestive for a possible developmental trend. While brain metabolite levels in TMGD resembled those of CW, some interesting findings, such as modulation of metabolite concentrations by age of onset of GD, warrant future inquiry.