Measurement of hair growth

In 1986, a study reviewed multiple techniques for measuring hair growth, including analysis of hair roots, histological methods, and the development of trichograms. The study involved three women and found that scalp hair grew at a rate of 0.37 mm/day, forearm hair at 0.18 mm/day, and thigh hair at 0.30 mm/day. No significant differences in growth rates were observed between individuals with certain dermatoses or monilethrix and healthy controls, nor was a circadian rhythm in hair growth detected. The study noted variations in hair diameter, with anagen hairs being thicker than telogen hairs, and in men with androgenic alopecia, both hair types had a similar diameter. Techniques such as laser beam diffraction were used for precise measurements. The document highlighted the complexity of measuring hair growth and the need for various techniques depending on the study's requirements, acknowledging that these methods have been more commonly applied in animal research than in human studies.