Background: Androgenetic alopecia needs to be scored precisely.
Objective: 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.
Methods: 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.
Results: 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.
Conclusions: 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.
Copyright 2002 S. Karger AG, Basel