Hair diameter measurement methods: micrometer caliper versus phototrichogram

ABSTRACT

Background@#Hair diameter is a crucial element in deciding the treatment and predicting the prognosis of hair transplantation in patients with hair loss. @*Methods@#Ten female volunteers participated in this study. Three sites at different horizontal positions of the scalp were chosen for measurement: midoccipital, mastoid, and temporal. Three boxes of 1 cm2 were marked from superior to inferior along the midline of each site, and five anagen hairs ≥10 cm long were randomly sampled from each box. The thickness of each collected hair was measured at three positions along the hair length: 1 cm, 5 cm, and 10 cm from the surface of the skin. The diameters of the hairs were measured using a micrometer caliper and a Folliscope phototrichogram, and the measurements were compared. @*Results@#The average thickness of all hairs was 76.90±12.29 μm when measured with the caliper and 108.78±19.97 μm when measured with the phototrichogram. There was a statistically significant difference between the two measurement methods (P<0.001). The average hair thickness from the three areas (midoccipital, mastoid, and temporal) showed a significant difference between the caliper and the Folliscope hair measurements (P<0.001): midoccipital area (caliper, 74.46±9.71 μm; Folliscope, 109.03±19.59 μm), mastoid area (caliper, 76.36±10.67 μm; Folliscope, 103.73±18.67 μm), and temporal area (caliper, 79.89±15.18 μm; Folliscope, 113.59±20.43 μm). @*Conclusions@#Measuring hair thickness using a phototrichogram, which generates a measurement of the long-axis dimension, is clinically useful in the treatment of patients with hair loss and patients undergoing hair transplantation.