--by age more than by gender; generally the older you are the lower the normal ranges are, though the change in the distribution from say, 30 to 70 is not that extreme. Over 70, if I remember correctly, there's more of a "drop off".

I'm running out to do tutoring very soon, so I don't have time to search the old archives now, but I will later and see if I can find the original Johns hopkins papers that documented the enumeration of intraepidermal small fiber density in normal subjects, which was a project that went on over several years in the 80's and 90's.