Cobalamin Deficiency in Elderly Patients: A Personal View
Table 2
Stages of cobalamin metabolism and
corresponding causes of cobalamin deficiency [13, 15].
Stages and
factors involved in cobalamin metabolism
Causes of cobalamin deficiency
Ingestion
of food
Strict
vegetarianism (patients who are sick in institutions or in psychiatric
hospitals)
Digestion,
which involves haptocorrin, gastric secretions (HCl and pepsin), intrinsic
factor, pancreatic and biliary secretions, and the enterohepatic cycle
Gastrectomy,
pernicious anemia, and food-cobalamin malabsorption
Absorption,
which brings into play intrinsic factor and cubilin
Ileal
resection, malabsorption, pernicious anemia, and food-cobalamin malabsorption
Transportation
by transcobalamins
Congenital
deficiency in transcobalamin II
Intracellular
metabolism by various intracellular enzymes
Congenital
deficiency in various intracellular enzymes
