Oxandrolone Use in Trans-Masculine Youth Appears to Increase Adult Height: Preliminary Evidence

Pubertal Suppression in Early Puberty Followed by Testosterone Mildly Increases Final Height in Transmasculine Youth

Context

Treatment for transmasculine youth (TMY) can involve testosterone treatment and is sometimes preceded by gonadotropin-releasing hormone agonist (GnRHa) treatment for puberty blockade. GnRHas can increase final height in birth-assigned females with central precocious puberty. Maximizing final adult height (FAH) is an important outcome for many TMY.

Objective

Our objective was to determine how GnRHa treatment before testosterone impacts FAH.

Methods

Retrospective cohort study at 5 US transgender health clinics. Participants were 32 TMY treated with GnRHas in early to midpuberty before testosterone (GnRHa + T group) and 62 late/postpubertal TMY treated with testosterone only (T-only group).

Results

The difference between FAH minus midparental target height (MPTH) was +2.3 ± 5.7 cm and -2.2 ± 5.6 cm in the GnRHa + T and T-only groups, respectively (P < .01). In the GnRHa + T group, FAH was 1.8 ± 3.4 cm greater than predicted adult height (PAH) (P < .05) and FAH vs initial height (IH) z-score was 0.5 ± 1.2 vs 0.16 ± 1.0 (P < .05). After adjusting for patient characteristics, each additional month of GnRHa monotherapy increased FAH by 0.59 cm (95% CI 0.31, 0.9 cm), stage 3 breast development at start of GnRHa was associated with 6.5 cm lower FAH compared with stage 2 (95% CI -10.43, -2.55), and FAH was 7.95 cm greater in the GnRHa + T group than in T-only group (95% CI -10.85, -5.06).

Conclusion

Treatment with GnRHa in TMY in early puberty before testosterone increases FAH compared with MPTH, PAH, IH, and TMY who only received testosterone in late/postpuberty. TMY considering GnRHas should be counseled that GnRHas may mildly increase their FAH if started early.

Just as Tall on Testosterone; a Neutral to Positive Effect on Adult Height of GnRHa and Testosterone in Trans Boys

CONTEXT

Growth is an important topic for many transgender boys. However, few studies have investigated the impact of puberty suppression (PS) and gender-affirming hormone treatment (GAHT) on growth and adult height.

OBJECTIVE

To evaluate the effect of PS and GAHT on growth and adult height.

DESIGN

Retrospective cohort study.

SETTING

Specialized gender identity clinic.

PARTICIPANTS

A total of 146 transgender boys treated with GnRH analogues and testosterone who reached adult height.

MAIN OUTCOME MEASURES

Growth, bone age (BA), adult height, and difference between adult height and predicted adult height (PAH) and midparental height.

RESULTS

In those with BA ≤14 years at start (n = 61), a decrease in growth velocity and bone maturation during PS was followed by an increase during GAHT. Adult height was 172.0 ± 6.9 cm; height SD score was similar to baseline (0.1; 95% CI, -0.2 to 0.4). Adult height was 3.9 ± 6.0 cm above midparental height and 3.0 ± 3.6 cm above PAH at start of PS. A younger BA at start PS was associated with an adult height significantly further above PAH.

CONCLUSION

During PS, growth decelerated followed by an acceleration during GAHT. Although adult height SD score was similar to baseline, adult height was taller than predicted based on BA at baseline, especially in those who started treatment at a younger BA. It is reassuring that PS and GAHT do not have a negative impact on adult height in transgender boys and might even lead to a slightly taller adult height, especially in those who start at a younger age.

Growth, growth potential, and influences on adult height in the transgender and gender-diverse population

The sexually dimorphic trait of height is one aspect of the experience of transgender and gender‐diverse (TGD) individuals that may influence their gender dysphoria and satisfaction with their transition. In this article, we have reviewed the current knowledge of the factors that contribute to one's final adult height and how it might be affected in TGD youth who have not experienced their gonadal puberty in the setting of receiving gonadotropin‐releasing hormone analog (GnRHa) and gender‐affirming hormonal treatment. Additional research is needed to characterize the influence of growth and final adult height on the lived experience of TGD youth and adults and how to best assess their growth, predict their final adult height, and how medical transition can be potentially modified to help them meet their goals.