Androgenetic alopecia (AGA) and benign prostatic hyperplasia (BPH) are both androgen-dependent disorders, displaying in situ high levels of dihydrotestosterone with a good therapeutic response to finasteride. Embryological development of both the hair follicle and the prostate depends on mesenchymal-epithelial interaction, which is influenced by the expression of type 2 5α-reductase. The aim of this study was to elucidate the association between the size of the prostate gland and the prevalence and severity of AGA. A total of 46 patients age between 56 and 87 years were retrospectively recruited. They fulfilling the clinical diagnosis of BPH defined as (1) prostate volume > 30 cm3, measured by transrectal ultrasound, (2) maximal urine flow rate < 15 ml/s and mean urine flow rate < 10 ml/s, and (3) prostate serum albumin < 10 ng/ml. The control group comprised 34 patients aged between 49 and 81 years with urogenital infection, cystitis or urolithiasis. The expression and severity of AGA were evaluated by dermatologists using modified Norwood/Hamilton classification. Patients with a prostate volume > 30 cm3 had a higher prevalence of AGA than patients with a smaller prostate (< 30 cm3) (83.3% vs 61.3%; P < 0.05). The prostate size, however, did not correlate with the severity of AGA in either group or in the whole patient group. The prevalence of AGA was not significantly different in patients with or without BPH (85.7% vs 70.6%). The prostate was slightly larger among patients with AGA than among those without AGA (mean ± SD 42.7 ± 17.4 vs 35.4 ± 14.9 cm3), but this was not statistically significant. There was no significant correlation between the age of onset of AGA and the development of BPH. Our results suggest that a larger prostate is associated with a higher prevalence of AGA. It remains to be seen if long-term use of finasteride in AGA patients will prophylactically lower the incidence of BPH.
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