Bone Health in the Transgender and Gender Diverse Youth Population

Determinants of bone mass accrual in transgender and gender diverse youth undergoing pubertal suppression therapy

INTRODUCTION/BACKGROUND

Gender-affirming care for gender diverse and transgender (GDTG) youth includes puberty suppression with gonadotropin-releasing hormone agonists (GnRHa). Puberty is a critical period of bone mass accrual, and pubertal suppression may impact bone health. Previous studies have shown a decrease in areal bone mineral density (aBMD) Z-score while on puberty suppression. However, the rate of bone mass accrual and its determinants during GnRHa therapy are not known.

METHODOLOGY

This is a retrospective chart review of GDTG youth with aBMD assessment within six months of starting GnRHa monotherapy at Cincinnati Children's Hospital Medical Center between 01/2011 and 12/2022. In individuals with follow-up aBMD assessment, we calculated their aBMD velocity and generated Z-scores using reference data from the Bone Mineral Density in Childhood Study. The determinants of baseline height-adjusted aBMD and aBMD velocity Z-scores were assessed with multiple linear regression models.

RESULTS

Thirty-six participants (36% assigned female at birth (AFAB), mean age at first aBMD assessment 12 ± 1.1 years) had baseline height-adjusted aBMD Z-score of -0.053 ± 0.79. Among 16 participants with follow-up aBMD assessment, the mean aBMD velocity Z-score was -0.42 ± 1.13 (-0.27 ± 0.79 in AFAB vs -0.52 ± 1.32 in assigned male at birth, p = 0.965). Baseline aBMD Z-scores significantly correlated with age at the first aBMD assessment (adjusted R2 0.124, p = 0.02) with combined modeling including age at first aBMD assessment and BMI Z-score being most significant (adjusted R2 0.21, p = 0.008). Only BMI Z-scores were positively associated with the aBMD-velocity Z-scores (adjusted R2 0.255, p = 0.046).

CONCLUSIONS

GDTG youth undergoing GnRHa therapy appeared to have below-average aBMD velocity Z-scores. A lower BMI Z-score was a determinant of lower baseline height-adjusted aBMD and aBMD velocity Z-scores. Building on previous studies, our study highlights aBMD velocity as a novel technique for bone health surveillance in GDTG youth.

Insulin sensitivity, body composition and bone mineral density after testosterone treatment in transgender youth with and without prior GnRH agonist therapy

Background

1.8% of youth identify as transgender; a growing proportion are transgender male (female sex, male gender identity). Many receive gonadotropin releasing hormone agonist (GnRHa) therapy to suppress endogenous puberty and/or will start testosterone to induce secondary sex characteristics that align with gender identity.

Objectives

To determine the effects of 12 months of testosterone on cardiometabolic health among transgender youth, including insulin sensitivity, body composition, and bone mineral density and whether changes in outcomes differ based on prior GnRHa treatment.

Methods

Participants (n = 19, baseline age 15.0 ± 1.0 years) were examined prior to and 12 months after testosterone therapy in a longitudinal observational study. Fasted morning blood draw, a 2-hour 75-gram oral glucose tolerance test, body composition and bone mineral density (dual-energy X-ray absorptiometry) were assessed at baseline and 12 months. Insulin sensitivity was estimated by HOMA-IR and Matsuda index. Changes were compared with mixed linear regression models evaluating time (baseline, 12 months), group (GnRHa treatment yes/no), and their interaction.

Results

In the entire cohort, fasted insulin decreased (median [25,75 %ile]: -3 [-5, 0] mIU/L, p = 0.044) and 2-hour glucose increased (mean ± standard deviation): +18.5 ± 28.9 mg/dL, p = 0.013 from baseline after 12 months of testosterone therapy. There were no significant changes in HOMA-IR (p = 0.062) or Matsuda index (p = 0.096), nor by GnRHa status. Absolute (+6.2 [4.7, 7.5] kg, p = 0.016) and percent fat-free mass increased (+7.3 [5.4, 9.1] %, p = 0.003) and percent fat mass declined (-7.4 [-9.3, 5.3]%, p = 0.005) for the entire cohort. There were time*group interactions for absolute (p = 0.0007) and percent fat-free mass (p = 0.033). There were time*group interactions for bone mineral content (p = 0.006).

Conclusions

Twelve months of testosterone in transgender adolescents resulted in changes in body composition and bone mineral density, with baseline differences between the +/-GnRHa group and convergence after 12 months. There were no changes in insulin sensitivity over time or between groups.

Puberty Suppression for Pediatric Gender Dysphoria and the Child's Right to an Open Future

In this essay, we consider the clinical and ethical implications of puberty blockers for pediatric gender dysphoria through the lens of "the child's right to an open future," which refers to rights that children do not have the capacity to exercise as minors, but that must be protected, so they can exercise them in the future as autonomous adults. We contrast the open future principle with the beliefs underpinning the gender affirming care model and discuss implications for consent. We evaluate claims that puberty blockers are reversible, discuss the scientific uncertainty about long-term benefits and harms, summarize international developments, and examine how suicide has been used to frame puberty suppression as a medically necessary, lifesaving treatment. In discussing these issues, we include relevant empirical evidence and raise questions for clinicians and researchers. We conclude that treatment pathways that delay decisions about medical transition until the child has had the chance to grow and mature into an autonomous adulthood would be most consistent with the open future principle.

Bone Density in Transgender Youth on Gender-Affirming Hormone Therapy

Some transgender youth are treated with gonadotropin-releasing hormone agonists (GnRHa) followed by testosterone or estradiol, which may impact bone mineral density (BMD). This cross-sectional study of transgender youth (n = 56, aged 10.4-19.8 years, 53% assigned female at birth [AFAB]) utilized total body dual-energy x-ray absorptiometry to evaluate BMD Z-scores, and associations between GnRHa duration, body mass index (BMI), and BMD. Participants on GnRHa alone (n = 19, 14 assigned male at birth [AMAB], 5 AFAB) at the time of the study visit were 13.8 [12.8, 15.3] (median [IQR]) years old, had been on GnRHa for 10 [5.5, 19.5] months, and began GnRHa at age 12 [10.4, 12.6] years. Total body BMD Z-score for individuals on GnRHa monotherapy was -0.10 [-0.8, 0.4] (AFAB, female norms) and -0.65 [-1.4, 0.22] (AMAB, male norms). AFAB participants (n = 21) on testosterone were age 16.7 [15.9, 17.8] years, had been on testosterone for 11 [7.3, 14.5] months, and started testosterone at age 16 [14.8, 16.8] years; total body BMD Z-score -0.2 [-0.5, 0] (male norms) and 0.4 [-0.2, 0.7] (female norms). AMAB participants (n = 16) were age 16.2 [15.1, 17.4] years, had been on estradiol for 11 [5.6, 13.7] months, and started estradiol at age 16 [14.4, 16.7] years; total body BMD Z-score -0.4 [-1.1, 0.3] (male norms) and -0.2 [-0.7, 0.6] (female norms). BMD Z-score was negatively correlated with GnRHa duration (male norms: r = -0.5, P = .005; female norms: r = -0.4, P = .029) and positively correlated with BMI (male norms: r = 0.4, P = .003; female norms: r = 0.4, P = .004). In this cross-sectional cohort, total body BMD Z-scores were slightly below average, but lowest in the AMAB group on GnRHa monotherapy.

Puberty Assessment and Consideration of Gonadotropin-Releasing Hormone Agonists in Transgender and Gender-Diverse Youth

Transgender and gender-diverse (TGD) youth may pursue gender-affirming medical therapy in the form of gonadotropin-releasing hormone analogues (GnRHa), or "puberty blockers," if pubertal changes result in the development or worsening of gender dysphoria. GnRHa monotherapy can allow TGD youth to explore gender without the distress of unwanted secondary sexual characteristics. However, given the potential effects of GnRHa on growth, skeletal development, neurodevelopment, fertility, and future surgical outcomes, it is critical to accurately assess pubertal status to facilitate fully informed conversations with TGD youth and families about risks, benefits, and unknown consequences of GnRHa monotherapy. The focus of this discussion will be on the approach to puberty assessment in TGD youth as well as the different effects of GnRHa monotherapy that may be important to TGD youth and their families. [Pediatr Ann. 2023;52(12):e462-e466.].