Trans girls grow tall: adult height is unaffected by GnRH analogue and estradiol treatment

• Published in: The journal of clinical endocrinology and metabolism 2022-06
• Main Authors: Boogers, Lidewij Sophia, Wiepjes, Chantal Maria, Klink, Daniel Tatting, Hellinga, Ilse, van Trotsenburg, Adrianus Sarinus Paulus, den Heijer, Martin, Hannema, Sabine Elisabeth
• Format: Article
• Language: English
• ISSN: 1945-7197
• DOI: 10.1210/clinem/dgac349

Transgender adolescents can receive GnRH analogues (GnRHa) and gender affirming hormone therapy (GAHT), but little is known about effects on growth and adult height. This is of interest since height differs between sexes and some trans girls wish to limit their growth. Investigate effects of GnRHa and GAHT on growth, and the efficacy of growth-reductive treatment. Retrospective cohort study. Specialised tertiary gender clinic. 161 trans girls treated with GnRHa and estradiol at a regular dose (2 mg) or high growth-reductive doses of estradiol (6 mg) or ethinylestradiol (EE, 100-200 µg). Growth, adult height and difference from predicted adult height (PAH) and target height. Growth velocity and bone maturation decreased during GnRHa, but increased during GAHT. Adult height after regular dose treatment was 180.8 ± 5.4 cm which was 2.2 cm below PAH at start GnRHa (95%CI 0.8 to 3.6), and close to target height (-0.2 cm, 95%CI -1.5 to 1.1). Compared to regular dose treatment, high dose estradiol and EE reduced adult height by 1.8 cm (95%CI -0.6 to 4.1) and 4.1 cm (95%CI 0.6 to 7.6), respectively. Growth decelerated during GnRHa and accelerated during GAHT. After regular dose treatment, adult height was slightly lower than predicted at start of GnRHa, likely due to systematic overestimation of PAH as described in boys from the general population, but not significantly different from target height. High dose EE resulted in greater reduction of adult height than high dose estradiol, but this needs to be weighed against possible adverse effects.