For centuries, perhaps millennia, transgender and gender diverse (TGD) individuals have largely been invisible within most societies. Tremendous stigma, fear, discrimination and lack of awareness prohibited many TGD individuals from being themselves and living in an open and authentic way. Duringmy endocrinology fellowship from 2003 to 2005, I did not receive any training in transgender medicine as the clinic where I trained did not allow transgender patients to schedule consultations for hormone management. When asked why this was the case, the clinic director at the time told me that “none of the attendings wanted to see TGD patients” due to negative experiences. A lack of training in transgender medicine was the norm several decades ago. At that time many openly TGD individuals in the United States would receive care from a small number of physicians who were interested and experienced in caring for members of the community and from health care centers that specifically welcomed LGBTQIA people.

The last two decades have witnessed an exponential increase in the number and percent of openly identified TGD people in many parts of the world.1,2 Just as awareness and acceptance of TGD people has increased, the medical profession has adapted, as well, in a positive way. Membership in the World Professional Association of Transgender Health has dramatically expanded over the past decade. The development of guidelines from major professional societies, such as the Endocrine Society, has mainstreamed the field the transgender medicine.3 By 2016, 63% of a sample of endocrinologists in the Mid-Atlantic region of the United States was willing to provide hormone therapy to TGD individuals, with a rate of 79% for those under age 39.4

This special issue of Andrology, thanks to the leadership of the journal, is devoted to increasing our knowledge of the medical, surgical, reproductive, and psychological issues pertaining to TGD patients. I thank the many authors from diverse specialties who have contributed seven original articles, six review articles, and one commentary on a wide variety of topics.

Starting with TGD adolescents, Roberts and Carswell review how the treatment of TGD youth who have not experienced their gonadal puberty can affect their height, particularly in the setting of pubertal suppression with gonadotropin-releasing hormone analogues.5 Quinn et al. review the reproductive considerations for TGD adolescents and young adults.6 They focus on reproductive health goals, sexual function, HIV/STI risk, barriers to accessing competent care, and how training programs can improve care. Ehrensaft and Tishelman review the psychosocial experiences of TGD youth who request hormonal treatment and who have completed endogenous puberty.7 They discuss the gender-related experiences before hormone treatment, the changes that accompany hormone treatment, the role of the family, the capacity of youth to make informed decisions, and the tasks for medical providers treating TGD youth.

From a medical standpoint, Feldman et al. describe and compare measures of health and health access among TGD and cisgender adults from the first national probability survey of its kind in the United States called TransPop.8 They found that despite equally high insurance coverage, TGD people more often avoided care due to cost. As compared to cisgender respondents, TGD respondents were more likely to rate their health as fair/poor and have more poor physical and mental health days. Grimstad et al. review the role of androgens in clitorophallus development from embryo to adulthood and how exogenous testosterone and surgical interventions can enlarge the clitorophallus to help TGD patients achieve their goals.9 My commentary reviews whether 5α reductase inhibitors should be considered standard treatment options for either transfeminine and transmasculine adults.10 I do not see much of a role for this class of medication in transfeminine patients whose testosterone levels are already at goal on estrogen and antiandrogen regimens.

Moving on to the surgical articles, Hontscharuk et al. comprehensively review patient satisfaction and complications of penile inversion vaginoplasty including post-operative bleeding and pain, wound healing and infection, granulation tissue, neovaginal stenosis, intravaginal hair growth, clitoral complications, urinary complications, and rectal injury.11 Kloer et al. conducted a systematic review of sexual health following vaginoplasty.12 They found median rates of 81% for general sexual satisfaction and 80% for ability to achieve orgasm postoperatively. Yuan et al. describe how burdensome insurance company requirements in the United States for referral letters for gender-affirming genital surgery can negatively impact care.13

Both medical and surgical treatment options may adversely affect the reproductive potential of TGD people. Rodriguez-Wallberg et al. conducted a prospective study of sperm quality in transgender women before or after hormone therapy.14 They found that transgender women who had not yet started hormone therapy had lower mean sperm concentrations, sperm counts, and motility as compared to a reference population from the World Health Organization. They confirmed that hormone therapy is associated with a high occurrence of sperm abnormalities. Schneider et al. measured serum and intratesticular inhibin B and anti-Mullerian hormone in transgender women.15 They found that levels of inhibin B, but not anti-Mullerian hormone, indicate the presence of spermatogonia. Two studies looked at the utilization and availability of reproductive services for TGD individuals who sought care at fertility centers in France. Eustache et al. found that transgender women were more likely to desire and achieve fertility preservation than transgender men.16 Bonan et al. describe the characteristics and intentions of couples involving a transgender man and cisgender female partner.17

Finally, Aldridge et al. conducted a prospective study over 18 months to assess the role of gender-affirming hormone therapy on depression and anxiety symptoms.18 They confirmed important mental health benefits of hormone therapy with reductions in both depression and anxiety symptoms. Nonetheless, they also found that high-levels of anxiety persist after hormone therapy and the need for social support.

Although research in transgender health has dramatically expanded over the past two decades, many large and important gaps exist in the field. In order to conduct studies with adequate sample sizes, electronic health records will need to routinely collect data on gender identity. On a global level, more research is needed from Africa, Asia, and the Middle East where the lives and care of TGD people likely differ. I look forward to how the field will evolve and advance.

The author declares that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.