I receive b-12 shots from my doc every three months, then I take b-12 vitamins every day, not sure if that is related to small fiber or not. I'm just trying to figure this awful disease out.......my back and ribs, left calve burns severely right now and nothing is working...........anyone to answer your questions, I don't know the level the neuro doc just said they were good and then did the biopsies and found each one suggests small fiber