ORLANDO – Janet Y. Lee, MD, MPH, said at the annual meeting of the American Society for Bone and Mineral Research.
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According to a report from The Williams Institute in 2017, there were approximately 150,000 youth in the United States who identified as transgender, and among studies that measured transgender identity among youth, the percentage who identified as transgender ranged between 1.3% and 3.2% (Herman J et al. “Age of Individuals who Identify as Transgender in the United States.” Los Angeles: The Williams Institute, January 2017).
“If you’ve not seen one of these patients yet, you probably will in your career,” said Dr. Lee of the University of California, San Francisco.
At UCSF, Dr. Lee said the focus of care for transgender youth in early childhood to late childhood is on school resources and social transition, with puberty blockers such as gonadotropin-releasing hormone agents (GnRHa) beginning in late childhood and early puberty at Tanner stage 2. When patients reach early puberty and move to late puberty and adulthood, they usually begin gender-affirming sex hormones such as testosterone for masculinizing hormone therapy or estrogen and spironolactone or bicalutamide for feminizing hormone therapy in transgender women, and consideration of fertility preservation is undertaken. In adulthood, patients can begin gender-affirming surgery.
Dr. Lee said the specific timing of gender-affirming sex hormones is controversial and “seems to be a moving target in our field.” The average age to begin gender-affirming sex hormones at UCSF is 14 years old, but sometimes younger, said Dr. Lee. There also is a question of when to start gender-affirming sex hormones in gender diverse youth. “[They] may not want full adult doses of testosterone or full adult doses of estradiol,” said Dr. Lee. “It’s been very challenging to figure out [appropriate] treatment for these youth.”
In Europe, some studies have shown transwomen have lower bone mineral density (BMD) scores at baseline even after 2.5 years to 5 years of treatment with estradiol, compared with male reference standards. A study by Vlot et al. found transwomen had lower bone turnover markers and bone mineral apparent density in cohorts younger than 15 years old, compared with cohorts 15 years or older (Bone. 2017 Feb. doi: 10.1016/j.bone.2016.11.008).
As in the case of when to start gender-affirming sex hormones, how to approach treatment for gender diverse youth who have a low baseline BMD but are eligible for puberty blockers is debated. “We could go into a whole other talk about this because we have many [patients] who present with low baseline BMD,” said Dr. Lee. “We have to figure out a way to apply treatment without impairing their bone.”
Other questions that have yet to be answered are what dual x-ray absorptiometry standards to be used for transgender individuals and how body composition and height growth are affected by gender-affirming medical therapy, which is currently “really modeled after hypergonadic children,” said Dr. Lee.
Results from a National Institutes of Health–funded longitudinal observational study of transgender youth at UCSF, Children’s Hospital Los Angeles, Boston Children’s Hospital, and Ann & Robert H. Lurie Children’s Hospital of Chicago is currently examining the effect of using gender-affirming medical treatment for patients in early and late puberty and assessing factors such as mental health, psychological well-being, and bone health measures such as dual x-ray absorptiometry and quantitative computed tomography, as well as investigating dietary intake, physical activity and exercise, and vitamin D status. Preliminary findings from the study have shown low BMD z-scores in designated males at birth when compared with designated females at birth, with suboptimal dietary calcium intake in both designated males and designated females.
Dr. Lee reported no relevant conflicts of interest.