Female pattern hair loss: beyond an androgenic aetiology?

Conflicts of interest: none declared. Madam, We read with great interest the intriguing case report by Cousen and Messenger describing female pattern hair loss (FPHL) occurring in a patient with complete androgen sensitivity syndrome, suggesting that mechanisms other than the effects of androgens contribute to this form of hair loss in women.1 The authors hypothesized that one potential mechanism may be via oestrogens, given that oestrogens inhibit hair growth in animal models, where they can arrest follicles in telogen and can prematurely induce catagen in growing (anagen) hair follicles.2, 3 The authors’ argument is supported by the observation that 17β‐estradiol indeed exerts hair growth inhibitory properties in female organ‐cultured occipital scalp hair follicles.4 Furthermore, hair loss constitutes a common undesired effect of therapy in female patients undergoing treatment with aromatase inhibitors,5 and although not evidence‐based medicine, topical oestrogen treatment has been a mainstay of FPHL management in central Europe for decades.6 Thus, we are delighted to learn that the authors appear to agree with our concept that the relative importance of oestrogen in normal female scalp hair follicle function and in FPHL pathogenesis remains widely underestimated and may even exceed that of androgens.2, 4