What is the treatment for Vitamin B12 deficiency?

From the Guidelines

The treatment of vitamin B12 deficiency should be initiated immediately with hydroxocobalamin 1 mg intramuscularly, with the frequency and duration of treatment depending on the presence of neurological involvement. For patients with possible neurological involvement, such as unexplained sensory and/or motor and gait symptoms, hydroxocobalamin 1 mg intramuscularly should be administered on alternate days until there is no further improvement, then hydroxocobalamin 1 mg intramuscularly administered every 2 months 1.

Key Considerations

• For people 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.
• It is essential to seek urgent specialist advice from a neurologist and haematologist if there is possible neurological involvement 1.
• Folic acid deficiency may indicate non-adherence with the daily multivitamin and mineral supplement or malabsorption, and treatment of folic acid deficiency should only be initiated after excluding vitamin B12 deficiency 1.

Treatment Approach

• The treatment approach should be individualized based on the cause and severity of the deficiency, as well as the presence of neurological symptoms.
• Monitoring response to treatment includes checking reticulocyte counts, hemoglobin levels, and B12 levels, with neurological symptoms potentially taking months to years to improve 1.

From the FDA Drug Label

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 bacteria overgrowth, total or partial gastrectomy Fish tapeworm infestation Malignancy of pancreas or bowel Folic acid deficiency Patients with pernicious anemia should be informed that they will require monthly injections of vitamin B12 for the remainder of their lives. Failure to do so will result in return of the anemia and in development of incapacitating and irreversible damage to the nerves of the spinal cord 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.

The treatment of B12 deficiency involves:

• Monthly injections of vitamin B12 for patients with pernicious anemia 2
• Oral supplementation for requirements of vitamin B12 in excess of normal due to certain conditions such as pregnancy, thyrotoxicosis, or hemolytic anemia 2
• Addressing underlying conditions such as gastrointestinal pathology, fish tapeworm infestation, or malignancy of pancreas or bowel 2
• Dietary changes such as a gluten-free diet in nontropical sprue or administration of antibiotics in tropical sprue 2 Key considerations include:
• Monitoring serum potassium during initial treatment of patients with pernicious anemia 2
• Regular laboratory tests to assess hematocrit, reticulocyte count, vitamin B12, folate, and iron levels 2

From the Research

Treatment Options for B12 Deficiency

• Parenteral regimens using 1000 micrograms cyanocobalamin: 5 or 6 biweekly injections for loading, and once-a-month for maintenance, may be necessary to meet metabolic requirements in many patients 3
• Oral therapy with 300-1000 micrograms per day may be therapeutically equivalent to parenteral therapy 3
• Treatment with a combination of methylcobalamin (MeCbl) and adenosylcobalamin (AdCbl) or hydroxocobalamin or cyanocobalamin (Cbl) is recommended, as both MeCbl and AdCbl are essential and have distinct metabolic fates and functions 4
• The oral route is comparable to the intramuscular route for rectifying vitamin B12 deficiency 4, 5

Dosage and Administration

• Initial laboratory assessment should include a complete blood count and serum vitamin B12 level, and measurement of serum methylmalonic acid should be used to confirm deficiency in asymptomatic high-risk patients with low-normal levels of vitamin B12 5
• Oral administration of high-dose vitamin B12 (1 to 2 mg daily) is as effective as intramuscular administration for correcting anemia and neurologic symptoms 5
• Intramuscular therapy leads to more rapid improvement and should be considered in patients with severe deficiency or severe neurologic symptoms 5
• Patients who have had bariatric surgery should receive 1 mg of oral vitamin B12 per day indefinitely 5

Special Considerations

• Screening average-risk adults for vitamin B12 deficiency is not recommended, but screening may be warranted in patients with one or more risk factors, such as gastric or small intestine resections, inflammatory bowel disease, or use of certain medications 5
• Metabolic vitamin B12 deficiency is common, being present in 10%-40% of the population, and is frequently missed 6
• Measuring serum B12 alone is not sufficient for diagnosis; it is necessary to measure holotranscobalamin or functional markers of B12 adequacy such as methylmalonic acid or plasma total homocysteine 6