Most hairs on the scalp are 70-85 micrometers in diameter. During the process of several hair loss conditions, the diameter of the hair shaft reduces. For example, reduction in hair shaft diameter can be seen in androgenetic alopecia, as well as conditions such as traction alopecia and alopecia areata. In genetic hair loss, a hair that is originally 80 micrometers becomes 60 micrometers and then slowly over years finds itself at 20.
Once a hair follicle thins below 55 micrometers I consider labelling it a "miniaturized" hair.
There is a big difference between a "miniaturized" hair vs "miniaturization". If a hair is 55 micrometers or less and most neighbor hairs are 80 micrometers - we say that hair is "miniaturized." However there is no real "miniaturization" of hairs. One can not really tell if a hair 65 micrometers is thinner from a natural process or from androgenetic alopecia. (Maybe it was just genetically set out to be 65 micrometers). However if none of the neighbouring hairs are thinner, there is less than a 0.05 % chance that it is thinner from early androgenetic alopecia. However if well over 20 % of the neighbors are thinner, there is a 99.5 % or more chance in males this is from androgenetic alopecia. In this case there is a miniaturized hair present and there is also miniaturization.
Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Vancouver office at 604.283.9299