The prevalence of B12 deficiency after Roux en Y gastric bypass surgery is about 20%. Serum B12 levels <400 pg mL are considered suboptimal because 5 10% of patients w neurologic symptoms related to B12 insufficiency Vitamin B12 Shots: Uses, Intake Levels, and Safety B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics