Background : Increasing numbers of transmasculine (TM) youth are able to utilize GnRH analogs followed by masculinizing gender affirming hormone therapy (GAHT). Clinicians providing early hormone care must monitor development, including growth. Growth spurts and final adult height are determined by numerous factors including parental heights, timing of puberty, and hormonal factors. We have noted anecdotally that a high percentage of TM youth attain their adult heights early. Few studies have systematically assessed growth variations in TM youth, and little is known about the effects of therapies on height outcomes. The goal of this study is to assess growth patterns in TM youth before and after GnRH analog therapy and various types of GAHT.
Methods : This was an IRB approved retrospective cohort study of 120 TM youth seen at a pediatric academic medical center between 2013-2018 with the ICD diagnosis of gender dysphoria. Information regarding growth and demographics as well as GnRH analog use and GAHT regimens were recorded. Heights, height percentiles, and midparental heights were compared to female population data. To examine growth patterns in rapidly growing children we focused on the subset of TM patients who had growth data available prior to age 11.5 years. Growth patterns were examined before and after GnRH analog therapy and GAHT.
Results : One hundred twenty TM patients met inclusion criteria.Their aggregate data generally fell within standardized CDC female growth curves. However, for those patients who had height measurements available prior to 11.5 years of age, a striking pattern of early growth deceleration was seen. Fifteen of 42 (36%) patients displayed decelerating growth patterns, crossing more than 2 major centile lines downward over time. The mean loss in height percentiles was 22.5+/-20.8% (mean+/-SD). Height percentiles were also examined in a larger group of patients (n=103) receiving GnRH analogs and androgen therapy. The mean height percentiles after hormone therapy displayed conservation of height percentiles compared to prior to hormone therapy (0.8+/-6.7%).
Conclusions : More than a third of our TM youth were found to display early height deceleration resulting in major negative shifts in the growth percentiles unrelated to therapy. Reassuringly, later addition of GnRH analog therapy and GAHT appear to preserve remaining growth. These findings highlight a need for early identification of TM youth and monitoring of growth as a critical component of care. Patients with early height deviations may benefit from referral to specialists for diagnostic evaluation and potential therapy to preserve growth.