Quantitative effects of sex hormones on hair growth and patient satisfaction

Gender-affirming hormone therapy (GAHT) alters hair distribution, a key aspect of gender transition. Transgender women often seek hair reduction, while transgender men typically desire increased hair growth. Previous studies relied on subjective hair assessments, with limited understanding of psychosocial effects.

To investigate changes in terminal hair growth in transgender men and women (both lasered and non-lasered) using digital microscopy, and their relation to body image during the first 12 months of GAHT.

In this longitudinal study, 36 participants (20 transgender men, 16 transgender women) initiating GAHT were assessed at baseline, and after 3 and 12 months of GAHT. Hair densities were measured using digital microscopy. Psychosocial outcomes were evaluated using the Body Appreciation Scale-2 and satisfaction questionnaires.

After 12 months, transgender women showed significant reductions in hair density on the upper lip (-17 hairs/cm2, CI -32, -2), chin (-28 hairs/cm2, CI -47, -8), and upper abdomen (-6 hairs/cm2, CI -12,0), with no significant differences between lasered and non-lasered women. Transgender men exhibited significant increases on the upper lip (+21 hairs/cm2, CI 11-30), chin (+13 hairs/cm2, CI 3-24), upper (+17 hairs/cm2, CI 8-23) and lower abdomen (+20 hairs/cm2, CI 11-28), and thighs (+14 hairs/cm2, CI 7-21). Both groups reported improved body appreciation, satisfaction with hair growth, and gender congruence.

GAHT induces measurable, location-specific changes in terminal hair growth in transgender women and men, accompanied by improvements in body image and satisfaction. Digital microscopy provides a valuable tool for future studies comparing GAHT regimens.