Improvement in scalp hair growth in androgen-deficient women treated with testosterone: a questionnaire study

Background Androgens are thought to have an adverse effect on female scalp hair growth. However, our clinical experience of androgen replacement therapy in women with androgen deficiency, in which hair loss was seldom reported, led us to question this concept. Objectives To evaluate the effect of subcutaneous testosterone therapy on scalp hair growth in female patients. Methods A total of 285 women, treated for a minimum of 1 year with subcutaneous testosterone implants for symptoms of androgen deficiency, were asked to complete a survey that included questions on scalp and facial hair. Age, body mass index (BMI) and serum testosterone levels were examined. Results Out of the 285 patients, 76 (27%) reported hair thinning prior to treatment; 48 of these patients (63%) reported hair regrowth on testosterone therapy (responders). Nonresponders (i.e. no reported hair regrowth on therapy) had significantly higher BMIs than responders (P = 0.05). Baseline serum testosterone levels were significantly lower in women reporting hair loss prior to therapy than in those who did not (P = 0.0001). There was no significant difference in serum testosterone levels, measured 4 weeks after testosterone implantation, between responders and nonresponders. No patient in this cohort reported scalp hair loss on testosterone therapy. A total of 262 women (92%) reported some increase in facial hair growth. Conclusions Subcutaneous testosterone therapy was found to have a beneficial effect on scalp hair growth in female patients treated for symptoms of androgen deficiency. We propose this is due to an anabolic effect of testosterone on hair growth. The fact that no subject complained of hair loss as a result of treatment casts doubt on the presumed role of testosterone in driving female scalp hair loss. These results need to be confirmed by formal measurements of hair growth.