Puberty Blockers and Bone Density: A Sourced Guide for Families

TransHealthHub

Sep 9

5 min read

Key Takeaways

Puberty blockers (also called puberty-pausing medication) pause the hormone signals that normally drive bone-mass building during puberty, which is why bone density is one of the most closely monitored effects of this treatment.
You may see this care described as puberty blockers, hormone-suppressing medication, or puberty-pausing medication. This guide uses "puberty-pausing medication" for clarity, and the terms describe the same treatment.
A 2020 U.S. study found that a meaningful share of transgender youth already had lower bone density scores before starting treatment at all, with at least one low score in 30 percent of youth designated male at birth (10 of 33) and 13 percent of youth designated female at birth (4 of 30), a small sample that makes these figures imprecise.
A separate 2020 study following transgender adolescents through puberty suppression and into hormone therapy found bone density scores declined during the pausing phase, then normalized in transgender boys by three years into combined treatment, but stayed below the population average in transgender girls at that point.
Clinicians manage bone density actively rather than leaving it to chance, with yearly bone density testing plus calcium, vitamin D, and physical activity support.

The short answer

Puberty blockers and bone density are connected through a simple mechanism: the hormones this medication pauses are the same ones that normally drive bone-mass building in adolescence. Research shows scores often decline somewhat during the pausing phase, then tend to improve once hormone therapy begins, though the pattern differs by sex assigned at birth and long-term data is still limited. At TransHealthHub, we think families deserve to see exactly what the research measures and what it doesn't, rather than a simple reassurance or a simple warning.

Bone density is tracked with the same basic tool used for any adolescent whose bone health needs monitoring, a bone density scan, and its results are compared against age- and sex-based reference ranges called Z-scores.

Why bone density is watched during this treatment

Puberty is when the body builds most of its lifetime peak bone mass, driven largely by rising estrogen and testosterone. Puberty-pausing medication works by pausing the hormone signals that trigger puberty, which means it also pauses part of that bone-building process while it's in use. That mechanism, not any unique property of the medication itself, is why bone density gets more attention than most other monitored effects. TransHealthHub's page on are puberty blockers safe covers how this fits into the broader safety picture for this medication.

What research shows before treatment even starts

Bone density concerns don't start with the medication. A 2020 study of 63 early-pubertal transgender youth at four U.S. academic pediatric gender centers measured bone density before any treatment began and found a meaningful share already had lower scores, with at least one low score in 30 percent of youth designated male at birth (10 of 33) and 13 percent of youth designated female at birth (4 of 30). Because those denominators are small, thirty and thirty-three young people, the percentages themselves are imprecise, and because the measurements came before treatment, they cannot be attributed to puberty-pausing medication. The same study found no significant vitamin D deficiencies but noted that dietary calcium intake was suboptimal across the group, which the authors flagged as a possible contributing factor worth addressing regardless of treatment.

What happens to bone density during treatment

A 2024 study of 56 transgender youth in the United States, most of whom had been on treatment for less than a year, found bone density scores were slightly below average across groups, but still within the normal range, including for those on puberty-pausing medication alone. The same study found bone density scores were lowest among youth designated male at birth on this medication without hormone therapy, and that longer time on the medication was associated with lower scores, an association the study's authors noted could reflect several contributing factors, including body mass index and physical activity levels, not the medication in isolation.

A separate, longer 2020 study in the Journal of Clinical Endocrinology and Metabolism followed 51 transgender girls and 70 transgender boys in the Netherlands and found bone density scores declined for both groups during roughly two years of puberty-pausing treatment.

What happens after hormone therapy begins

That same Netherlands study followed a subset of participants, 36 girls and 42 boys, through three additional years of combined hormone treatment and found bone density scores increased significantly once hormone therapy began. By the three-year mark, scores had normalized in transgender boys, but remained below the population average in transgender girls, whose scores had actually started out lower even before treatment began. The study's authors were direct about what this does and doesn't show: "it is currently unclear whether this results in adverse outcomes, such as increased fracture risk," in transgender girls as they age, and no fractures were reported among participants during the study itself. That's an honest open question in the research, not a demonstrated harm.

How clinicians monitor and support bone health

Bone density is something a care team actively manages rather than leaves to chance. The Mayo Clinic notes that yearly bone density and bone age tests may be recommended during treatment, along with calcium and vitamin D support as needed. The authors of the 2024 U.S. study explicitly recommended optimizing physical activity, body mass index, and vitamin D status for this population, a general recommendation attributable to them rather than a measured outcome of the study itself.

What the research does and doesn't show, at a glance

Study	What it measured	What it found
Lee et al., 2020 (63 U.S. youth)	Bone density before any treatment began	30 percent of youth designated male at birth (10 of 33) and 13 percent designated female at birth (4 of 30) already had at least one low score
Roy et al., 2024 (56 U.S. youth)	Bone density in a cross-sectional sample on various treatments, most for under a year	Scores slightly below average but within the normal range across groups; lowest among those on puberty-pausing medication alone
Schagen et al., 2020 (121 Dutch adolescents)	Bone density across roughly two years of puberty pausing and three years of combined hormone treatment	Scores declined during pausing, then normalized in transgender boys and stayed below average in transgender girls by the three-year mark

Frequently asked questions

How are puberty blockers and bone density connected? Research shows bone density scores can decline somewhat during the puberty-pausing phase, and some youth already have lower scores before treatment even starts. Scores tend to improve once hormone therapy begins, though a gap between transgender boys and girls at the three-year mark remains an open research question.

Does bone density recover after puberty blockers? In one study, bone density scores normalized in transgender boys within three years of adding hormone therapy, but remained below average in transgender girls at that same point, which researchers say needs more long-term follow-up to fully understand.

What can families do to support bone health during treatment? Clinicians typically recommend yearly bone density testing, adequate calcium and vitamin D, and regular physical activity, the same general bone-health steps recommended for any adolescent, alongside the condition-specific monitoring a care team provides.