J Invest Dermatol. 1990 Dec;95(6):683-7. Links
Price, et al
Regrowth of hair with minoxidil treatment over a 40-week period is reported for eight women with pattern hair loss. The women were given either a 2% minoxidil solution or a placebo only. Hair on the scalp was pulled through a lastic template, and the outline of the template was drawn. The hair was clipped and collected at five eight-week intervals (one untreated and four treated). Subsequent measurements included the total weight of hair regrown in the marked area, the total number of hairs. Calculated quantities included average weight per hair, average length, and average optical width. The average total hair weight of minoxidil-treated subjects increased over the 32-week test period by 42.5%, compared to 1.9% for the placebo-treated subjects. Changes for the average number count were 29.9% and -2.6%, respectively. These increases, observed using an unusually small number of subjects, clearly distinguished the treated subjects from the untreated. During the same test period, the averaged quantities of weight, diameter, and length from the 50-hair subsample showed insignificant change (p usually greater than 0.5). In addition to showing a larger percentage increase than did the total number, the total weight is not only easier to obtain, but less prone to error during sampling and measurement. Therefore, we recommend that total weight from a defined area be considered as the primary quantitative estimator for hair regrowth.
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