Nancy - SFN is small fiber neuropathy. When I was tested for this the numbers I had to be compared against (the standards) were for people older than me (they have no data on my age group) and my numbers for epidermal nerve fibers were already considered low (but not low enough to be in the bottom 5% of the standards data). I will probably have the biopsy redone in a year or so if I continue to have problems.