Growth in Transgender/Gender-Diverse Youth in the First Year of Treatment With Gonadotropin-Releasing Hormone Agonists

Purpose: Transgender/gender-diverse (TGD) youth are treated with gonadotropin-releasing hormone agonists (GnRHas) to halt endogenous puberty and prevent the development of secondary sex characteristics discordant with their gender identity. This treatment may have significant impact on growth and height velocity (HV). Methods: Participants were recruited prior to GnRHa initiation from four gender specialty clinics in the U.S. Anthropometric, laboratory, and Tanner-stage data were abstracted from medical records. Results: Fifty-five TGD youth (47% designated male at birth) with a mean ± standard deviation age of 11.5 ± 1.2 years were included in the analysis. HV in the first year of GnRHa use was median (interquartile range) 5.1 (3.7–5.6) cm/year. Later Tanner stage at GnRHa initiation was associated with lower HV: 5.3 (4.4–5.6) cm/year for Tanner stage II, 4.4 (3.3–6.0) cm/year for Tanner stage III, and 1.6 (1.5–2.9) cm/year for Tanner stage IV (p =.001). When controlled for age, there was not a significant difference in mean HV between TGD youth and prepubertal youth; however, when stratified by Tanner stage individuals starting GnRHa at Tanner stage IV had an HV below that of prepubertal youth, 1.6 (1.5–2.9) versus 6.1 (4.3–6.5) cm/year, p =.006. Conclusions: Overall, TGD youth treated with GnRHa have HV similar to that of prepubertal children, but TGD youth who start GnRHa later in puberty have an HV below the prepubertal range. Ongoing follow-up of this cohort will determine the impact of GnRHa treatment on adult height.