How to treat Vitamin B12 deficiency not due to intrinsic factor deficiency?

From the Guidelines

To treat a patient with a B12 deficiency not related to an intrinsic factor, it is recommended to administer hydroxocobalamin 1 mg intramuscularly as the initial treatment.

Treatment Regimens

• For patients with neurological involvement, hydroxocobalamin 1 mg intramuscularly should be administered on alternate days until there is no further improvement, then every 2 months 1.
• For patients with no neurological involvement, hydroxocobalamin 1 mg intramuscularly should be administered three times a week for 2 weeks, followed by maintenance treatment with 1 mg intramuscularly every 2-3 months for life 1.

Key Considerations

• Folic acid should not be given first as it may mask underlying vitamin B12 deficiency and precipitate subacute combined degeneration of the spinal cord 1.
• Patients should be monitored for signs of improvement, such as increased energy levels and resolution of neurological symptoms, and have regular follow-up appointments to adjust treatment as needed.
• It is also essential to identify and address the underlying cause of the deficiency, such as dietary restrictions or malabsorption.
• Oral therapy may be as effective but is poorly explored, and parenteral supplementation remains the reference, but oral supplementation may become standard in the coming years 1.

From the FDA Drug Label

INDICATIONS AND USAGE 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 (see Drug/Laboratory Test Interactions), 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.

To treat Vitamin B12 deficiency not due to intrinsic factor deficiency, oral supplementation can be used, especially in cases where the deficiency is due to increased requirements, such as in pregnancy, thyrotoxicosis, hemolytic anemia, hemorrhage, malignancy, hepatic and renal disease 2. Additionally, treating the underlying cause of the deficiency, such as:

• Surgical correction of anatomic lesions
• Expulsion of fish tapeworm
• Discontinuation of drugs leading to vitamin malabsorption
• Use of a gluten-free diet in nontropical sprue
• Administration of antibiotics in tropical sprue can remove the need for long-term administration of Vitamin B12 supplements.

From the Research

Treatment Options for Vitamin B12 Deficiency

• For individuals with vitamin B12 deficiency not due to intrinsic factor deficiency, treatment options include oral supplementation and parenteral (intramuscular) supplementation 3.
• Oral supplementation is likely sufficient for individuals with reduced dietary intake of B12, while parenteral supplementation is preferred for those with B12 malabsorption 3.
• The British National Formulary guidelines suggest that many individuals with B12 deficiency due to malabsorption can be managed with 1000 µg intramuscular hydroxocobalamin once every two months after the initial loading 3.
• However, some studies suggest that oral treatment can be effective for vitamin B12 deficiency, even in cases of malabsorption 4, 5.
• A prospective cohort study found that oral vitamin B12 supplementation at a dosage of 1000 μg/d was effective in treating vitamin B12 deficiency in patients with pernicious anemia, with 88.5% of patients no longer deficient in vitamin B12 after 1 month of treatment 6.
• Another study found that oral therapy with 300-1000 micrograms per day may be therapeutically equivalent to parenteral therapy 7.

Dosage and Administration

• The optimal dosage and administration of vitamin B12 supplementation vary depending on the individual and the cause of the deficiency 3.
• Some studies suggest that higher doses of vitamin B12 may be necessary to meet metabolic requirements in many patients 7.
• The frequency of administration also varies, with some individuals requiring more frequent injections to remain symptom-free and maintain a normal quality of life 3.
• However, there is no consensus on the optimal long-term management of B12 deficiency with intramuscular therapy, and treatment should be individualized based on the cause of the deficiency and the patient's response to treatment 3.