This case is based on publication in literature by Harrison R, Warburton V, Lux A, Atan D. Ann Intern Med. 2019 Sep 3. Link below. Non-clinical elements (e.g. initials, story details, etc) are adapted. Peer Review: Dr. Nikhil Parelkar. I originally had another case for video of a vitamin b12 deficiency I saw as a student about a girl on an overly strict diet. I didn't release it because the details were more difficult than I would like for a video. The clinical principles and science of that case and this one are the same.