Vitamin B12 deficiency, sometimes called cobalamin deficiency, happens when your body is either not getting enough or not absorbing enough vitamin B12 from the foods you eat. Vitamin B12 is an important Hypercobalaminuria' Is urinary cobalamin loss a potential determinant of parenteral cobalamin (B12) efficacy in Pernicious Anaemia? ScienceDirect B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics What Does a B12 Shot Do for You? Vitamin B12 Deficiency