Most transgender teens reach adult height close to their sex assigned at birth after HT
Click Here to Manage Email Alerts
Key takeaways:
- Adult height for most transgender adolescents receiving HT is similar to the reference range for their sex assigned at birth.
- Some transgender girls have a lower adult height after HT than their target height.
Most transgender adolescents receiving a gonadotropin-releasing hormone agonist combined with gender-confirming hormone therapy grow to an adult height close to the reference height for their sex assigned at birth, according to study data.
“Our study provides evidence that Danish transgender adolescents starting gender-affirming HT before the age of 18 years reach a normal adult height for their sex assigned at birth, and most obtain an adult height that is aligned with their target,” Pernille Badsberg Norup, MD, a PhD student in the department of growth and reproduction at Rigshospitalet and University of Copenhagen in Denmark, told Healio. “The findings from this study can be used to improve future counseling, optimize individual treatment and align expectations. The findings can further be used in the current debate concerning puberty suppression in transgender adolescents.”
Researchers conducted an observational study of 219 transgender adolescents who began gender-confirming HT at younger than 18 years from 2016 to January 2023 (median age, 16.4 years). All participants received gonadotropin-releasing hormone agonist therapy along with estradiol for transgender girls and testosterone for transgender boys. Height and weight were measured at each visit every 3 to 6 months and compared with Danish references. Growth velocity was compared with international references. Bone age was assessed through a radiograph of the left hand. Target height was calculated using the height of both parents for each participant. Researchers also calculated predicted adult height. Blood samples were collected at each visit to measure insulin-like growth factor I and IGF binding protein-3 (IGFBP-3). Adolescents were considered to have reached adult height when they had two consecutive visits with the same height measurement.
The findings were published in The Journal of Clinical Endocrinology & Metabolism.
The study group included 164 transgender boys and 55 transgender girls. Of the group, 81.3% reached adult height during the study.
Of transgender girls, 98.1% reached an adult height within 2 standard deviations of cisgender boys and 11% reached an adult height above two standard deviations compared with cisgender girls. Of transgender boys, 95% reached an adult height within 2 standard deviations for cisgender girls and 48% had an adult height of more than 2 standard deviations less than the reference for cisgender boys, the researchers reported.
Among 18 transgender girls with available data, adult height was 2.7 cm lower than target height (P = .01). No difference was observed between predicted adult height and actual height. Three transgender girls started HT with a bone age of 15 years or younger. Those participants had a 5.8 cm lower adult height than their target height (P = .006).
Among 87 transgender boys, no differences were found between target height or predicted adult height and actual height. Transgender boys with a bone age of 14 years or younger at the start of HT also had no differences between target height and adult height, according to the study.
Transgender girls with a bone age of 15 years or younger had a decline in growth velocity during gonadotropin-releasing hormone agonist treatment followed by an increase in growth velocity during estradiol therapy. A decline during gonadotropin-releasing hormone agonist therapy was not observed among transgender boys with a bone age of 14 years or younger.
IGF-I and IGFBP-3 levels for all participants were within 2 standard deviations of reference populations.
“Our study adds important knowledge in a field with few existing systematic studies,” Badsberg Norup said. “We need more studies with adolescents starting HT in early puberty to confirm our findings.”
For more information:
Pernille Badsberg Norup, MD, can be reached at pernille.badsberg.norup.01@regionh.dk.
Collapse
Read more about
Click Here to Manage Email Alerts