Cyanocobalamin is indicated for Vitamin B12 deficiencies due to malabsorption which may be associated with the following conditions:
Addisonian (pernicious) anemia
Gastrointestinal pathology, dysfunction, or surgery, including gluten enteropathy or sprue, small bowel bacterial overgrowth, total or partial gastrectomy
Fish tapeworm infestation
Malignancy of pancreas or bowel
Folic acid deficiency
It may be possible to treat the underlying disease by surgical correction of anatomic lesions leading to small bowel bacterial overgrowth, expulsion of fish tapeworm, discontinuation of drugs leading to vitamin malabsorption, use of a gluten-free diet in nontropical sprue, or administration of antibiotics in tropical sprue. Such measures remove the need for long-term administration of cyanocobalamin.
Requirements of Vitamin B12 in excess of normal (due to pregnancy, thyrotoxicosis, hemolytic anemia, hemorrhage, malignancy, hepatic and renal disease) can usually be met with oral supplementation.
Cyanocobalamin injection is also suitable for the Vitamin B12 absorption test (Schilling test).