Early puberty suppression and gender-affirming hormones do not alter final height in transgender adolescents

Abstract

Background: Early puberty suppression (ePS; Tanner stages 2 and 3) through gonadotropin-releasing hormone agonists (GnRHas) and gender-affirming hormones (GAHs) interferes with growth and may impact final height (FH).

Aim: To investigate the impact of ePS and GAH on FH in trans boys and trans girls.

Methods: Retrospective study, including 10 trans boys and 22 trans girls at FH. Bone age (BA) was determined at the start of ePS and at the start of GAH according to Greulich and Pyle; predicted adult height (PAH) was calculated according to Bayley and Pinneau's tables; target height (TH) was calculated as adjusted mean of maternal and paternal height. Target height, PAH, and BA were determined according to sex registered at birth (SRAB) and experienced gender (EG).

Results: The age at the start of PS was 12.37 ± 0.74 years in trans boys and 13.10 ± 1.12 years in trans girls. Total height gain since the start of ePS in trans boys was 14.62 ± 4.08 cm, with 70% achieved before the start of GAH. In trans girls, it was 20.68 ± 7.66 cm, with 61% achieved before GAH. Target height for SRAB was the most accurate predictor for FH in both trans boys and girls: the difference with FH was 1.57 cm ± 3.1 (P = .168) and -0.98 cm ± 4.17 (P = .319), respectively. Also the difference between FH and PAH at the start of PS for SRAB was nonsignificant in both trans boys and girls (2.62 cm ± 3.79, P = .056 and -2.35 cm ± 5.2, P = .051, respectively).

Conclusion: Early puberty suppression and GAH do not impact FH, supporting the safety of the treatment; however, trans adolescents achieve a FH in line with SRAB, rather than EG.

Keywords: GnRH agonist; cross-sex; final height; gender-affirming hormones; growth; puberty; transgender.