COMPARATIVE-EVALUATION OF SCALP HAIR BY PHOTOTRICHOGRAM AND UNIT AREATRICHOGRAM ANALYSIS WITHIN THE SAME SUBJECTS

Quantitative evaluation of scalp hair requires techniques that are rep roducible. The unit area trichogram is such a method but is unsuitable for large-scale clinical trials. An alternative may be the phototrich ogram - a non-plucking, non-invasive method. Hair variables were evalu ated in 12 Caucasian subjects employing both methods. The mean value f or total hair density was significantly underestimated by the phototri chogram (181 versus 237 hairs/cm2); however, no significant difference was found between this phototrichogram value and the number of non-ve llus hairs/cm2. Estimates for the percentage of anagen hairs were simi lar with both methods. Hair diameters from the phototrichogram were to o unreliable to be of any practical use. Analysis of the individual ha ir data revealed that light hair was much more difficult to evaluate t han dark hair. Consequently, Caucasian subjects with light hair or dar k skin subjects with dark hair should be excluded from studies employi ng phototrichograms.