Snapshot A 52-year-old man presents to his physician for a routine check-up. He reports increasing fatigue and has a smooth, sore tongue. He is a strict vegan and has had bariatric surgery 3 years ago. Physical examination is notable for decreased vibration sensation and proprioception. Laboratory studies demonstrate a macrocytic anemia with reticulocytopenia. Peripheral blood smear demonstrates hypersegmented neutrophils. Introduction Overview login to view 5 more bullets Etiology Decreased oral intake login to view 3 more bullets Decreased absorption login to view 16 more bullets Pathophysiology login to view 31 more bullets Presentation Symptoms login to view 7 more bullets Physical examination login to view 13 more bullets Labs Serum labs login to view 6 more bullets Peripheral blood and marrow smear show login to view 1 more bullet Differential Folate anemia login to view 3 more bullets Treatment Medical login to view 3 more bullets Complications Irreversible neurological damage if untreated Prognosis Atrophic gastritis increases risk of gastric cancer