fig5

Figure 5. Linear growth rates according to hair diameter and gender along with ageing in patients complaining of hair loss. Age is shown on the x-axis (years) and growth rates on the y-axis (LHGR, µm/day; scale from 150-400 µm/day). Female data appear as circles while male data are symbolised by squares. The symbols for genders apply in this figure whatever the diameter of hair fibres category and the same gender-symbols are also used in Figures 8 and 9. The largest plain symbols represent terminal hair (diameter ≥ 60 µm), smaller plain symbols represent thinning intermediate hair (diameter 40 µm) and smaller empty symbols are for the thinnest hair (paler print 30 µm and more contrasted 20 µm). The average LHGR of 50 µm diameter are not shown in this figure as data caused substantial amount of overlap. Detailed statistical values on age interacting with clinical classification on hair dynamics are given in Table 8. The diameter of the hair fibre exerts a major statistically significant influence on the daily growth rate. Whatever the age, the terminal hair clearly grew more quickly than the thinner intermediate hair (larger and smaller plain symbols, respectively) and all miniaturising hair (open symbols). However, with increasing age, the relative difference became gradually less marked. The statistically significant linear regression for the terminal hair vs. age appears, after combination of data for both genders, as shown by the line across the larger plain symbols. The pure effect of ageing cannot be separated from longstanding exposure to the noxious mechanisms responsible for the regression process. LHGR: Linear hair growth rate.