How soon can AFAB trans adolescents expect physical changes from testosterone?

As of this month, it’s been seven years since I started HRT, and I can still recall the excitement, anticipation, and impatience of waiting for the first physical results to appear. (It turned out to be 10 days after starting, with the first noticeable hint of breast and areolar changes.) I also remember the acute discomfort and deep sadness, ten years prior to that, of seeing my body grow more and more unsightly and uncomfortable hair every day, heading in exactly the wrong direction. It would have been fantastic if the dread of the latter could have been replaced with the joy of the former, and with the advent of puberty blockers, trans youth today increasingly have the opportunity to access that very possibility.

But even the Endocrine Society’s most recent version of its transgender treatment guidelines offers only rough estimates of the timeframes of physical changes from hormone treatments for trans adults, apparently based only on the authors’ general clinical experience, and nothing on trans youth using puberty blockers and cross-sex hormones to induce the correct puberty. A recent study helps to change that, examining just what the course of puberty looks like for adolescent trans boys.

Stoffers, de Vries, & Hannema (2019) evaluated 62 AFAB adolescents who had previously used puberty blockers and had been on testosterone for at least 6 months, starting testosterone at a median of age 17.2 with a range of 14.9 to 18.4 years. These youth exhibited an increase in hair growth within 3 months of starting testosterone, with all of them showing an increase in hair on their extremities after one year and all having increased facial hair growth after 15 months. Additionally, 79% had grown chest or abdominal hair after a year. 85% experienced voice deepening after 3 months, and all had deeper voices by 6 months. Notably, when their testosterone dose was increased more rapidly, voice deepening and facial hair growth were more rapid as well:

The prevalence of acne increased from 16% to 35% after six months, peaking at 60% after one year and declining after 15 months. The authors note that the timing of voice deepening as well as the development of acne is in line with the findings of previous studies of testosterone in adult trans men. Altogether, testosterone treatment can produce relatively rapid results for adolescent trans boys, with significant changes occurring even within the first year:

Testosterone treatment using a dosing schedule as recommended by current guidelines effectively induces virilization in transgender boys, with increased hair growth and voice change noted within 3 months of therapy in the majority.

These findings should be welcome news to those adolescents for whom these changes can’t come soon enough. ■