BH07: Testosterone deficiency in men with female pattern hair loss

R. Jerjen, L. Trindade de Carvalho, K. Kerkemeyer, R. Sinclair and B. Bhoyrul

Sinclair Dermatology, Melbourne, Australia

The role of androgens in progressive hair follicle miniaturization in androgenetic alopecia (AGA) is well known. It is thought that terminal-to-vellus hair transformation and alteration in hair cycle dynamics are driven by dihydrotestosterone in genetically susceptible individuals. Classical male pattern hair loss (MPHL) presents with bitemporal recession and vertex balding; however, a minority of men with AGA can present with female pattern hair loss (FPHL), which is characterized by hair rarefaction over the mid-frontal and parietal scalp with preservation of the frontal hairline. This phenotype is poorly characterized in men as most studies of AGA fail to include this variant. The purpose of this cross-sectional study was to further evaluate the association between testosterone levels and hair loss phenotype in a larger group of men with clinically confirmed AGA. Forty-seven men with FPHL (mean age 31·4 years) and 104 men with MPHL (mean age 30·4 years) were included. Nine (19%) men with FPHL had low total testosterone (defined as < 11·3 nmol L^–1) vs. none in the MPHL group. Patients with FPHL had a statistical trend towards lower mean testosterone levels (17·7 nmol L^–1 vs. 19·9 nmol L^–1; P = 0·06). One patient with severe testosterone deficiency (3·3 nmol L^–1) in the FPHL group, who also had hyperprolactinaemia, was subsequently found to have a pituitary adenoma. There was no correlation between the level of total testosterone and severity of hair loss. There were no statistically significant differences in levels of prolactin, 25-hydroxyvitamin D, thyroid hormones, zinc or ferritin between the two groups. Our study is limited by its small sample size and referral bias to a specialist hair clinic. We have demonstrated in this study that men with FPHL tend to have lower levels of total testosterone compared with their MPHL counterparts, suggesting a possible role of testosterone in the pathogenesis of FPHL in men. FPHL may be an early manifestation of low testosterone in men, which may warrant endocrinology referral. Larger studies are required to confirm these results.