Low Bone Mineral Density in Early Pubertal Transgender/Gender Diverse Youth: Findings From the Trans Youth Care Study.
Context
Transgender youth may initiate GnRH agonists (GnRHa) to suppress puberty, a critical period for bone-mass accrual. Low bone mineral density (BMD) has been reported in late-pubertal transgender girls before gender-affirming therapy, but little is known about BMD in early-pubertal transgender youth.


Objective
To describe BMD in early-pubertal transgender youth.


Design
Cross-sectional analysis of the prospective, observational, longitudinal Trans Youth Care Study cohort.


Setting
Four multidisciplinary academic pediatric gender centers in the United States.


Participants
Early-pubertal transgender youth initiating GnRHa.


Main Outcome Measures
Areal and volumetric BMD Z-scores.


Results
Designated males at birth (DMAB) had below-average BMD Z-scores when compared with male reference standards, and designated females at birth (DFAB) had below-average BMD Z-scores when compared with female reference standards except at hip sites. At least 1 BMD Z-score was < -2 in 30% of DMAB and 13% of DFAB. Youth with low BMD scored lower on the Physical Activity Questionnaire for Older Children than youth with normal BMD, 2.32 ± 0.71 vs. 2.76 ± 0.61 (P = 0.01). There were no significant deficiencies in vitamin D, but dietary calcium intake was suboptimal in all youth.


Conclusions
In early-pubertal transgender youth, BMD was lower than reference standards for sex designated at birth. This lower BMD may be explained, in part, by suboptimal calcium intake and decreased physical activity-potential targets for intervention. Our results suggest a potential need for assessment of BMD in prepubertal gender-diverse youth and continued monitoring of BMD throughout the pubertal period of gender-affirming therapy.
['Lee|Janet Y|JY|0000-0002-3563-8843', 'Finlayson|Courtney|C|0000-0001-9704-4525', 'Olson-Kennedy|Johanna|J|0000-0001-6264-7596', 'Garofalo|Robert|R|0000-0001-9513-9416', 'Chan|Yee-Ming|YM|0000-0003-0554-8502', 'Glidden|David V|DV|0000-0001-5888-1419', 'Rosenthal|Stephen M|SM|0000-0001-5027-1464']
bone mineral density transgender youth DXA bone QCT gender-affirming medical treatment gonadotropin-releasing hormone agonists