A 28-year-old man comes to the office to discuss hair loss. He has hair loss primarily around the temples, which began insidiously 3 years ago. The patient is concerned because several of his family members became almost completely bald by their late 30s. He otherwise feels healthy and has normal muscle strength, libido, and erectile function. The patient is married, has 2 children, and works as a charter airplane pilot. Physical examination shows moderate thinning of hair at the anterior scalp, temporal region, and vertex. An oral medication is prescribed to treat the hair loss. After the initiation of therapy, which of the following changes would most likely occur in this patient?

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11ec160b_3ba5_de54_9249_dd822b6eb273_MD0001_00 This patient has androgenetic alopecia (often called male pattern hair loss), which presents with progressive hair loss at the temples, frontal hairline, and vertex. Androgenetic alopecia is characterized by a shortened anagen hair growth phase in the affected portions of the scalp, leading to shorter, thinner hair shafts (follicular miniaturization) with increased apoptosis at the dermal papillae. As the name implies, androgenetic alopecia is driven by both inherited (polygenic inheritance) and hormonal factors. Dihydrotestosterone (DHT) appears to be the primary androgen responsible for hair loss. Although total androgen levels are similar in affected and unaffected men, patients with androgenetic alopecia have a greater effect of DHT due to increased local conversion of testosterone to DHT and increased concentrations of androgen receptors in affected areas of the scalp. Androgenetic alopecia can be treated with 5-alpha reductase inhibitors (eg, finasteride), which decrease conversion of testosterone to DHT in the tissues. However, by preventing conversion to DHT, they increase the level of testosterone, which is then available for conversion to estradiol by aromatase. This can lead to mild feminizing effects (eg, gynecomastia) in some patients. Other treatments for androgenetic alopecia include topical minoxidil, a vasodilator that appears to increase the vascularity of the dermal papillae. (Choices A, B, C, and E) Inhibition of 5-alpha reductase by finasteride lowers DHT formation, leading to higher levels of testosterone and increased conversion to estradiol. Educational objective: Androgenetic alopecia causes hair loss primarily at the anterior scalp and vertex. It shows polygenic inheritance, with dihydrotestosterone (DHT) being the primary pathogenic factor. Five-alpha reductase inhibitors decrease the conversion of testosterone to DHT and are effective for treating the condition. __________ References: The efficacy and safety of 5a-reductase inhibitors in androgenetic alopecia: a network meta-analysis and benefit-risk assessment of finasteride and dutasteride. (http://www.ncbi.nlm.nih.gov/pubmed/23768246)

A 28-Year-Old Man Comes to the Office to Discuss Hair