The mechanism of action of minoxidil appears to be a direct effect on the follicles, increasing proliferation and differentiation of epithelial cells in the hair shaft. Since up to two thirds of men experience androgenic alopecia, male pattern baldness is considered a normal variant rather than a disease. Although devoid of serious health aspects, patient concerns about balding should be taken seriously since one half of balding patients have psychologic sequelae. Although androgenic alopecia is the most common cause of male pattern baldness, pathologic causes of alopecia must also be considered in the evaluation of hair loss in men. Scarring alopecia is typically seen in patients with infectious or connective tissue diseases.
Androgenic alopecia is a nonscarring variety.
Table 1 lists other causes of nonscarring alopecia. The patient's history plays an important role in establishing the differential diagnosis. Key elements of the history include family history, medications, concomitant medical illness, stresses, and the pattern and speed of progression of hair loss. Patchy hair loss may be associated with conditions such as tinea capitis, lupus erythematosus and immune-mediated alopecia areata. A history of abrupt hair loss following a significant stress is indicative of telogen effluvium.