Endocrine Abstracts

JOINT2575

Background: Gonadotrophin-releasing hormone (GnRH) analogues are widely used to suppress puberty in adolescents with gender dysphoria. While effective in halting endogenous pubertal progression, concerns persist regarding their impact on linear growth and bone mineral density (BMD) during a crucial period of skeletal growth. Understanding this impact is essential to optimise care and mitigate potential long-term risks.

Objective: To assess the effects of triptorelin on linear growth and BMD in transfeminine and transmasculine adolescents followed in a paediatric endocrinology clinic.

Methods: This was a longitudinal study conducted in a paediatric endocrinology clinic between January 2020 and December 2024. The study included adolescents with gender dysphoria who were treated with triptorelin for at least two years. Growth parameters and BMD (measured by dual-energy X-ray absorptiometry, DXA) were evaluated at baseline and follow-up. BMD Z-scores were analysed using reference values based on sex assigned at birth. Biochemical markers of bone metabolism, including blood calcium, phosphate, vitamin D, parathormone (PTH), and alkaline phosphatase, were also assessed.

Results: 22 adolescents were analysed: 15 transmasculine and 7 transfeminine; aged 14–19 years; referred to the clinic between 12 and 15 years old. Triptorelin use was associated with transient growth deceleration, with partial catch-up after discontinuation. Transmasculine individuals showed greater preservation of height SDS compared to transfeminine individuals. BMD Z-scores declined during GnRH analogue treatment in both groups, with more pronounced reductions in transfeminine individuals. Of the 15 individuals who commenced gender-affirming hormone therapy (GAHT), a partial recovery in BMD was observed; however, some remained below expected reference values for their age. Mean blood calcium levels were 2. 30 ± 0. 10 mmol/l, phosphate 1. 20 ± 0. 15 mmol/l, 25-hydroxyvitamin D 45 ± 10 nmol/l, PTH 4. 5 ± 1. 2 pmol/l, and alkaline phosphatase 150 ± 40 U/l, indicating transient bone turnover alterations.

Conclusion: Our findings highlight the effects of triptorelin on growth and bone health in adolescents undergoing puberty suppression. The observed decline in BMD underscores the importance of regular monitoring and early interventions to support bone health. While GAHT appears to facilitate partial BMD recovery, further research is needed to establish optimal management strategies. These results contribute to a growing body of evidence guiding best practices in gender-affirming care for adolescents.