Puberty Blockers and Bone Density: What Trans Individuals Need to Know

Understanding the Impact of Puberty Blockers on Bone Density in Transgender Teens

Current Discussions on Gender Affirming Care

The topic of gender affirming care for children and young adults has recently sparked considerable debate. A primary concern is the potential irreversible impact of puberty blockers on bone density in otherwise healthy adolescents. Fortunately, a group of Dutch endocrinologists and pediatricians is studying the effects of puberty blockers on bone density. Their findings were published in JAMA Pediatrics in October 2023.

Study Overview

This research followed transgender adults who utilized puberty blockers during their teenage years before transitioning to hormone therapy. The study aimed to assess their bone density ten years later to determine any lasting effects. The question remains: Are puberty blockers safe for developing adolescents? The answer is nuanced, much like gender identity itself.

Effects of Puberty Blockers on Bone Health

Assessing Long-Term Safety

When discussing safety in this context, we refer to whether puberty blockers have long-term consequences that could impede healthy bone growth. According to the 2023 study, the answer varies based on individual circumstances. The evidence indicated that a decade after initiating puberty blockers followed by hormone treatment, trans men had bone mineral density scores aligned with their age group. Conversely, while trans women exhibited normal bone density in their hips, they generally had lower scores in their lumbar spine, suggesting the need for additional monitoring.

Context of the Study

To comprehend the implications of this research, it is essential to understand the relationship between puberty and bone mass, the function of puberty blockers, and the populations that utilize them.

The Relationship Between Puberty and Bone Mass

Understanding Bone Development

The onset of puberty marks the beginning of a countdown for skeletal growth. Most individuals complete skeletal development by their late teens or early twenties. The bone mass and mineral density accrued during gestation, infancy, and adolescence contribute to what is termed the “bone bank.” Reaching peak mineral density in late twenties means that individuals with higher bone density at the end of puberty will take longer to experience bone loss.

Consequences of Delayed Puberty

Research has consistently shown that both boys and girls who start puberty late tend to have lower bone mineral density in adulthood. Most bone mineral density is acquired during adolescence, coinciding with the surge of sex hormones. Delaying puberty, therefore, can result in insufficient bone density, especially in children who are already smaller than average.

Mechanism of Puberty Blockers

Function of Puberty Blockers

Puberty blockers are medications that inhibit the pituitary gland’s release of hormones responsible for triggering sexual maturity. These drugs, usually administered via injection, require regular doses to maintain their effects. The primary goal is to pause puberty, allowing time for further growth before the bones fuse.

Clinical Indications for Puberty Blockers

In 2017, several medical organizations established clinical guidelines regarding the treatment of gender dysphoria. Gender dysphoria occurs when an individual’s gender identity does not align with their assigned sex, causing significant distress. Adolescence often exacerbates this incongruence, and puberty blockers may provide a necessary pause, allowing time for exploration of gender identity.

Eligibility for Puberty Blockers

Clinical Guidelines for Treatment

Puberty blockers are typically prescribed to adolescents who have reached specific developmental markers of puberty and are experiencing distress due to their physical changes. The treatment is not intended for prepubescent children.

Typical Treatment Pathway

A typical treatment plan may involve an adolescent presenting with gender dysphoria, receiving puberty blockers, and, upon reaching age 16, starting hormone therapy if distress persists. This gradual approach allows for careful monitoring and management.

Research Study Focus

Aim of the Study

The study aimed to evaluate whether the use of puberty blockers had long-term negative consequences on bone mass in transgender teens. Previous studies indicated that delayed puberty leads to lower bone mass due to lack of sex hormones, and researchers sought to determine if the same applied to transgender youth.

Participant Demographics

Researchers contacted former clients of the Amsterdam UMC gender identity clinic who had received puberty blockers before age 18 and had been on hormone therapy for at least nine years. Out of 143 individuals, 75 participated, consisting of both trans men and trans women.

Bone Density Measurement Methodology

DXA Testing Process

Bone density was assessed using dual-energy X-ray absorptiometry (DXA), which measures bone density in specific regions. The results yield T scores and Z scores, providing insight into bone health relative to normative values.

Interpreting T and Z Scores

The T score compares an individual’s bone density to that of a healthy adult, while the Z score compares it to age- and sex-matched peers. Scores within the range of -1 to +1 are considered normal.

Findings on Trans Men

Bone Density Trends

The study tracked Z scores of trans men across various time points. Initial scores were below average, indicating expected outcomes due to paused puberty. However, following the initiation of testosterone therapy, bone density readings improved, suggesting that hormone therapy effectively compensated for the earlier delays.

Findings on Trans Women

Bone Density Observations

Trans women exhibited initial Z scores within normal limits but experienced declines following the use of puberty blockers. Although scores improved with estrogen therapy, lumbar spine readings remained low throughout the study duration, indicating a need for further attention.

Conclusions and Recommendations

Implications for Transgender Teens

The findings suggest that while trans men generally recover bone density post-treatment, trans women may require additional monitoring for lumbar spine health. The overall results emphasize the importance of individualized care and long-term strategies for managing bone health in transgender individuals.

Future Research Directions

The study highlighted the need for larger, more comprehensive datasets to better understand the long-term effects of puberty blockers on bone density. Continued research will be crucial in guiding clinical practices and informing policy decisions regarding transgender youth care.

References

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Casteel CO, Singh G. Physiology, Gonadotropin-Releasing Hormone. In: StatPearls. StatPearls Publishing; 2025. Accessed February 10, 2025.
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Finkelstein JS, et al. Osteopenia in men with a history of delayed puberty. N Engl J Med. 1992;326(9):600-604.
Gilsanz V, et al. Age at Onset of Puberty Predicts Bone Mass in Young Adulthood. J Pediatr. 2011;158(1):100-105.e2.
van der Loos MATC, et al. Bone Mineral Density in Transgender Adolescents Treated With Puberty Suppression and Subsequent Gender-Affirming Hormones. JAMA Pediatrics. 2023;177(12):1332-1341.