fig4

Figure 4. Hair densities in female and male patients with pattern hair loss (PHL). Hair density (n/cm²) allows a rather static description of a dynamic process in PHL. Hair counts were established with our phototrichogram in PHL, respectively, Ludwig (females, LI-LIII) and Hamilton (males, HI-HV). Patients were ranked by decreasing THD (large open circles), and all differences of THD within gender were statistically significantly different. Accordingly, the rank was HI, LI, HII, HIII, LII, HIV/HV and LIII. where the gradual reduction in THD reflects the severest chronic regression. We draw attention to the fact that LII and HIV/HV show equal total hair density. The gradual decrease in hair density after splitting into a range of diameter categories illustrates that the main contributor to decreased total hair density is terminal hair (open squares). While intermediate (open green triangles) appears quite dense in HI males, hair thinning (open red small circles) does not compensate hair density with increasing severity of PHL. This most likely reflects extended empty follicles between cycles. Finally, in the most severely affected patients (LII, HIV-HV or LIII), the hair fibre densities spread almost equally into the three thickness categories: terminal, intermediate and vellus-like hairs. The average density of nanohair (< 20 µm; small plain blue diamonds) in PHL always exceeded the 95th percentile value of healthy controls independently of gender or severity, as shown by the dotted blue line at the bottom. The density of nanohair appears as a new sensitive and specific diagnostic parameter in patients complaining of hair loss. As far as PHL is concerned (with the notable exception of HI), it is statistically significantly increased in all patient groups either female or male [Tables 1 and 2]. THD: total hair density.