How Bone Density Responds When Puberty Suppression Ends

Bone density in transgender and gender-diverse adolescents slows while they are on puberty blockers but shows a clear, if partial, recovery once gender-affirming hormone therapy begins, according to a systematic review and meta-analysis published in JAMA Pediatrics.

The pooled analysis, led by Daniele Tienforti, MD, of the University of L'Aquila in Italy, covered 10 longitudinal studies and 751 adolescents — 427 assigned female at birth (AFAB) and 324 assigned male at birth (AMAB). During treatment with gonadotropin-releasing hormone agonists (GnRHa), for mean durations of up to 38.4 months, absolute bone mineral density (BMD) remained stable. Measured against sex-assigned-at-birth normative references, however, lumbar spine BMD z-scores fell significantly: by -0.97 among AFAB youth and -0.73 among AMAB youth.

After a median 36 months of gender-affirming hormone therapy (GAHT), the picture improved. Lumbar spine z-scores partially recovered to -0.51 in AFAB and -0.52 in AMAB adolescents, while absolute BMD rose modestly in both groups (0.09 g/cm² and 0.13 g/cm², respectively), indicating that bone accrual had resumed. The z-scores remained numerically below baseline at most skeletal sites but were generally not statistically different, which the authors read as a modest and uncertain shortfall in catch-up rather than a demonstrated persistent deficit.

"Our results suggest that puberty suppression temporarily slows bone accrual, but this is followed by a clear recovery after gender-affirming hormone therapy is initiated," Tienforti told MedPage Today. Because adolescence is the primary window for building lifelong bone mass, he stressed that bone health monitoring should be part of routine gender-affirming care throughout treatment.

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What the Recovery Trajectory Means for Clinicians

Why Puberty Suppression Weighs on the Skeleton

The mechanism behind the slowdown is largely mechanical. GnRHa therapy reduces lean mass and increases fat mass, which weakens the muscle-bone unit — the loading relationship that drives skeletal development during adolescence. With sex steroids suppressed, the normal stimulus for bone accrual is removed during the very period when it matters most. The researchers also note that some transgender adolescents, particularly those AMAB, enter treatment with lower baseline BMD, which may heighten their vulnerability to treatment-related changes in bone.

What the Partial Rebound Does — and Does Not — Prove

The clearest signal is consistency: across different cohorts and healthcare settings, the same trajectory appeared — z-scores dip during GnRHa therapy, then climb after sex steroids are introduced. Absolute BMD gains during GAHT confirm that bone accrual resumes. But the remaining gap matters. With z-scores still numerically below baseline after a median three years of hormone therapy, it is not yet clear whether that shortfall closes, persists, or carries clinical consequences such as elevated fracture risk later in life. Meta-regression results pointed to more favorable outcomes with higher body mass index, shorter GnRHa duration, longer GAHT exposure, and older age at GnRHa initiation — variables clinicians can weigh when planning treatment.

The Evidence Gap on Long-Term Bone Health

Adolescence is the primary window for building peak bone mass, which is reached in early adulthood. The included studies had relatively short follow-up, no parallel cisgender comparator groups, inconsistent adjustment for key confounders, and sparse reporting of bone turnover markers or fracture rates. That means the durability of the rebound remains unproven. Widespread vitamin D insufficiency across cohorts adds another variable: the authors advise routine supplementation of roughly 600 IU/day of cholecalciferol alongside balanced nutrition and physical activity.

Monitoring Bone Health Through Gender-Affirming Care

For clinicians:

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  • Build bone health monitoring into routine gender-affirming care rather than treating it as a one-off baseline check — the study supports structured DXA surveillance throughout treatment, with the lumbar spine as the most responsive site.
  • Screen for vitamin D insufficiency and supplement roughly 600 IU/day of cholecalciferol where low, since insufficiency was common across the pooled cohorts.
  • Counsel patients on modifiable lifestyle factors — adequate calcium intake and regular weight-bearing exercise — alongside treatment.
  • When planning GnRHa and GAHT, weigh the meta-regression findings: shorter GnRHa duration, longer GAHT exposure, and older age at GnRHa initiation were all tied to more favorable bone outcomes.

For families:

  • Expect bone density to be tracked across the full course of care, not only at the start; z-scores typically lag baseline even after hormone therapy begins.
  • Support the modifiable factors clinicians flag — vitamin D, calcium, and weight-bearing physical activity — during puberty suppression and after.