aka cobalamin
important for cellular metabolism - DNA synthesis, methylation; mitochondria metabolism
classical pernicious anaemia with megaloblastic anemia uncommon
exact definition of deficiency contentious .. incidences 2.5 - 25%
vulnerable patient groups: vegan elderly female, pregnancy, gastric bypass with DM on metformin
classically treated with IM B12, oral 1g a day also works well
blood tests: B12, methylmalonic acid/ homocysteine
presents with hematological, neurological and psychiatric symptoms