Vecchio F, Guarrera M, Rebora A
DiSEM, Section of Dermatology, University of Genoa, Italy.
Dermatology. 2002;204(1):33-6. doi: 10.1159/000051807.
Androgenetic alopecia needs to be scored precisely.
A possible measure is the ratio between the hair density in the parietal area and that in the occipital area which, being not affected by baldness, supposedly has a 'normal' density.
On the vertex and just below the occipital protuberance of 109 men, two 1-cm(2) areas were identified. In both areas, hairs were clipped short and photographed by a videomicroscope. Hairs were then counted within a 30-mm(2)-wide central square section.
In the occipital area, the average count was 127/cm(2), without differences among the Hamilton/Norwood classes. In the parietal area, the average density significantly diminished from 138 to 47/cm(2). A main difference was found between classes 1-3 vertex and classes 4-6.
The parietal/occipital ratio decreased significantly only when baldness was clinically manifest. The parietal/occipital ratio cannot be a better measure of baldness severity than the rough Hamilton/Norwood scale. The perception of early baldness does not depend on the diminished hair density, but also on the progressive thinning of the hair shafts.
