New research is providing reassuring evidence for transgender youth and their families: while puberty blockers temporarily slow bone density development, bone health appears to recover after young people begin gender-affirming hormone therapy.
The findings, reported this week in JAMA Pediatrics, followed transgender adolescents who received puberty blockers before transitioning to estrogen or testosterone. Researchers found that although bone mineral density declined relative to age-matched peers during puberty suppression, those losses largely rebounded once gender-affirming hormones were introduced.
Puberty is one of the most important periods for building lifelong bone strength. Because puberty blockers suppress the body’s production of sex hormones, they also temporarily slow the rapid bone mineralization that normally occurs during adolescence. That effect has frequently been cited by critics of gender-affirming care as evidence that the treatment causes permanent skeletal damage.
The new study tells a more nuanced story.
Researchers found that after transgender youth discontinued puberty blockers and began hormone therapy aligned with their gender identity, bone density increased significantly over time. For transgender boys receiving testosterone, bone density generally returned to levels expected for their age. Transgender girls taking estrogen also experienced substantial improvement, although some measurements remained slightly below population averages, particularly in the lumbar spine.
The findings add to a growing body of research suggesting that changes seen during puberty suppression should be viewed as temporary rather than permanent. Previous studies have consistently shown that bone density Z-scores decline while youth are taking puberty blockers because their peers continue accumulating bone mass during puberty. However, those studies also indicated recovery begins after hormone therapy starts.
Medical experts say the results reinforce the importance of monitoring bone health throughout treatment rather than viewing puberty blockers in isolation. Endocrinologists routinely recommend adequate calcium intake, vitamin D supplementation when needed, and regular weight-bearing exercise to support healthy bone development during adolescence.
The research also highlights why long-term follow-up studies are essential. While bone density appears to recover for most transgender youth receiving gender-affirming hormones, researchers continue to study whether peak bone mass achieved in adulthood differs from that of cisgender peers and whether there are any implications later in life.
For families weighing treatment options, the study offers evidence against claims that puberty blockers inevitably cause irreversible bone damage. Instead, it suggests the temporary slowing of bone development during puberty suppression is largely reversed once hormone therapy begins, supporting current clinical practices that include ongoing bone health monitoring throughout gender-affirming care. The authors noted that continued research will help further refine treatment protocols, but the latest findings provide encouraging data for clinicians and families navigating an often politicized area of medicine.
