Early and long-term gender-affirming treatment does not alter final height in transgender youth

Silvia Ciancia; Daniel Klink; Margarita Craen; Martine Cools

Keywords: transgender, GnRH agonists, gender affirming hormones, final height, growth, puberty

Background: Trans boys (TB) and trans girls (TG) who start medical gender-affirming treatment at Tanner stage 2-3 undergo early puberty suppression (ePS) with Gonadotropin-Releasing Hormone agonists (GnRHa) for several years and subsequently receive gender-affirming hormones (GAH), around 15-16 years. This treatment clearly interferes with the timing of puberty and the hormonal milieu, alters physiological growth, and potentially impacts on final height (FH). Moreover, as height is a sexually dimorphic trait, FH is a concern for many transgender adolescents. This study aims to evaluate the effect of ePS with GnRHa and GAH on growth and FH in TB and TG.

Methods: Retrospective study, including 10 TB and 22 TG at FH. We determined bone age (BA) at start of ePS and at start of GAH (Greulich & Pyle), calculated predicted adult height (PAH) (Bayley & Pinneau’s tables) and target height (TH) as adjusted mean of parental height. TH, PAH and BA were determined according to sex registered at birth (SRAB) and experienced gender (EG).

Results: After a total of 5.85 ± 0.51 years (TB) and 5.40 ± 1.37 (TG) of medical gender-affirming treatment, FH did not differ from TH_SRAB in both TB and TG (as shown in bold in the table below). Age: years; height: cm


	TB	P-value	TG	P-value
Age at PS	12.37 ± 0.74		13.10 ± 1.12
Age at GAH	15.97 ± 0.46		15.90 ± 0.33
Age at FH	18.22 ± 0.57		18.50 ± 0.79
BA_SRABat PS	12.15 ± 0.41		12.64 ± 1.29
BA_SRAB at GAH	13.56 ± 0.63		14.18 ± 0.49
Duration of PS	3.61 ± 0.52		2.80 ± 1.22
Duration of GAH	2.24 ± 0.19		2.60 ± 0.77
Total height gain	14.62 ± 4.08 (70% before GAH)		20.68 ± 7.66 (61% before GAH)
ΔFH - TH_SRAB	1.57 ± 3.1	0.168	-0.98 ± 4.17	0.319
ΔFH -TH_EG	-11.43 ± 3.1	< 0.001	12.02 ± 4.17	< 0.001
FH - PAH_SRAB at PS	2.62 ± 3.79	0.056	-2.35 ± 5.2	0.051
FH - PAH_EG at PS	-4.52 ± 5.56	0.03	2.76 ± 6.92	0.082
Height Z-score_SRAB at PS	-0.32 ± 0.34		-0.46 ± 1.11
Height Z-score_SRAB at GAH	-0.43 ± 0.56		-0.90 ± 1.02
Height Z-score_SRAB at FH	0.22 ± 0.82		0.10 ± 1.38
ΔHeight Z-score_SRAB (FH-PS)	0.54 ± 0.72	0.04	0.56 ± 1.21	0.04

Conclusions: Early start of medical gender-affirming treatment, although substantially altering the physiological process of growth, does not appear to impact FH.

ESPE Abstracts

P1-571