RESUMO
BACKGROUND: To properly assess the progression and treatment response of alopecia, one must measure the changes in hair mass, which is influenced by both the density and diameter of hair. Unfortunately, a convenient device for hair mass evaluation had not been available to dermatologists until the recent introduction of the cross-section trichometer, which directly measures the cross-sectional area of an isolated bundle of hair. OBJECTIVE: We sought to evaluate the accuracy and sensitivity of the HairCheck(®) device, a commercial product derived from the original cross-section trichometer. MATERIALS AND METHODS: Bundles of surgical silk and human hair were used to evaluate the ability of the HairCheck(®) device to detect and measure small changes in the number and diameter of strands, and bundle weight. RESULTS: Strong correlations were observed between the bundle's cross-sectional area, displayed as the numeric Hair Mass Index (HMI), the number of strands, the silk/hair diameter, and the bundle dry weight. CONCLUSION: HMI strongly correlated with the number and diameter of silk/hair, and the weight of the bundle, suggesting that it can serve as a valid indicator of hair mass. We have given the name cross-section trichometry (CST) to the methodology of obtaining the HMI using the HairCheck(®) system. CST is a simple modality for the quantification of hair mass, and may be used as a convenient and useful tool to clinically assess changes in hair mass caused by thinning, shedding, breakage, or growth in males and females with progressive alopecia or those receiving alopecia treatment.