Phototrichogram analysis of Japanese female subjects with chronic diffuse hair loss.

Hair growth patterns of 101 Japanese female subjects with diffuse, chronic hair loss and 58 healthy Japanese female volunteers were categorized into subgroups using noninvasive quantitative methods after determining the key parameters of hair growth. Phototrichogram was performed at 0 and 48 h after clipping hairs in the parietal region of the scalp. Shaft diameters of the excised hairs were then measured. Multiple regression analysis indicated that hair densities, hair diameters, short hair ratios, and hair growth rates, but not anagen hair ratios, were significant, in order of decreasing importance, for grading female diffuse alopecia. Using cluster analysis, hair growth patterns among subjects complaining of diffuse hair loss were divided into six abnormal groups (n=60), two borderline groups (n=21), and one normal group (n=20). The control subjects judged to be normal by macroscopic observation, actually included two subjects with borderline hair growth patterns and one abnormal subject. Most of the abnormal groups shared features of female androgenetic alopecia. Hair patterns showing a decrease in hair density but without vellus hair change, however, emerged as the most prevalent and distinct pattern of chronic diffuse hair loss among the Japanese female subjects. The phototrichogram, combined with the measurement of hair diameters, is an accurate tool for assessing hair growth patterns, especially in detecting the slight changes indicative of the early phase of diffuse alopecia.