PUBERTY BLOCKERS & BONE DENSITY:
WHAT THE RESEARCH SHOWS
Puberty blockers can lower bone density during treatment. Because the sex hormones that build bone are paused, bone density scores tend to dip while a young person is on the medication, and longer time on it is linked to lower density. The reassuring part, supported by long-term research, is that density generally rises again once gender-affirming hormones begin, catching up to pretreatment levels at most sites. Because of this pattern, bone health is one of the main things a specialist monitors throughout treatment.
This is the effect with the most evidence behind it, so it is worth understanding in some detail: what happens, why, where the one lingering question is, and how care teams manage it. This page uses “puberty-pausing medications” for the treatment after the first mentions; you may also see them called puberty blockers or puberty suppression, which mean the same thing.
CONTENT NOTE
This is information, not medical advice. Whether this medication is appropriate for a particular young person is a decision for that young person, their family, and their qualified healthcare providers, based on individual circumstances.
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Density dips during the pause. Bone density z-scores tend to decline while on the medication, and longer use is linked to lower scores.
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It generally recovers with hormones. A long-term study found density caught up to pretreatment levels at most sites once gender-affirming hormones began.
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One lingering question. In youth assigned male at birth, the lower-spine density did not fully catch up in that study, possibly linked to low estrogen.
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Some youth start with lower density. Many trans youth, especially those assigned male at birth, already show lower-than-average bone density before starting, so baseline monitoring matters.
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It is monitored and supported. Care teams track density with scans and support it with vitamin D, calcium, and weight-bearing activity.
KEY TAKEAWAYS
WHY PUBERTY PAUSING MEDICATIONS AFFECTS
BONE DENSITY
Puberty is when the body builds most of its adult bone, driven by rising sex hormones. These medications pause those hormones, so they also pause some of that bone-building for as long as they are taken. That is why density is the effect researchers watch most closely, and why a dip during treatment is not surprising (Journal of Clinical Endocrinology & Metabolism, 2020).
WHAT THE RESEARCH FOUND
Sources: JAMA Pediatrics long-term cohort (van der Loos et al., 2023); Endocrine Society, 2022; JCEM, 2020.
DURING THE PAUSE: DENSITY SCORES DECLINE
Multiple studies find bone density z-scores (which compare a person to others of the same age, sex, and size) decline during treatment. An Endocrine Society study reported that longer duration on the medications was associated with lower bone-density scores (Endocrine Society, 2022). This is a slowing of the normal gain, tracked closely rather than ignored.
AFTER HORMONES BEGIN: DENSITY GENERALLY RECOVERS
The most informative long-term evidence is a prospective cohort followed over nine years, published in JAMA Pediatrics in 2023. It found that after long-term gender-affirming hormone use, bone density scores caught up with pretreatment levels, except at the lumbar spine in participants assigned male at birth (van der Loos et al., 2023). For most people and most sites, the dip during the pause was not permanent.
THE HONEST EXCEPTION AND THE BASELINE
Two caveats. First, in youth assigned male at birth, lower-spine (lumbar) density did not fully return to baseline in that study, which researchers linked to low estrogen and addressed by recommending optimized hormone treatment and lifestyle support. Second, several studies find that many trans youth, especially those assigned male at birth, already have lower-than-average bone density before starting any treatment, so some of what is measured reflects a pre-existing baseline, not the medication alone (European Journal of Endocrinology, 2024). Fracture data in this group is still sparse: no clear increase in fractures has been established even among young people with meaningful density decreases, and researchers say the long-term significance needs further study.
HOW BONE HEALTH IS MONITORED & PROTECTED
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Baseline and regular bone density (DXA) scans, often yearly.
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Vitamin D and calcium.
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Weight-bearing exercise.
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Optimizing hormone treatment when the time comes, especially estrogen in youth assigned male at birth.
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Not leaving a young person in a low-hormone state longer than needed.
Related reading: long-term effects.
