From the Guidelines
For B12 replacement, I recommend administering hydroxocobalamin 1 mg intramuscularly on alternate days until there is no further improvement, then administering hydroxocobalamin 1 mg intramuscularly every 2 months for patients with neurological involvement, and hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks for those without neurological involvement, followed by maintenance treatment with 1 mg intramuscularly every 2–3 months for life. This approach is based on the most recent and highest quality study available, which provides guidelines for the treatment of vitamin B12 deficiency 1. The study emphasizes the importance of treating vitamin B12 deficiency immediately, especially in patients with possible neurological involvement, and seeking urgent specialist advice from a neurologist and haematologist if necessary.
Key Considerations
- Vitamin B12 deficiency should be treated immediately to prevent irreversible neurological damage 1
- Hydroxocobalamin is the recommended form of vitamin B12 for replacement therapy, with a dose of 1 mg intramuscularly administered on alternate days until there is no further improvement, then every 2 months for patients with neurological involvement, and three times a week for 2 weeks for those without neurological involvement 1
- Maintenance treatment with 1 mg intramuscularly every 2–3 months for life is necessary to prevent recurrence of deficiency 1
- Folic acid deficiency may indicate non-adherence with daily multivitamin and mineral supplement or malabsorption, and treatment with oral folic acid 5 mg daily should be given for a minimum of 4 months after excluding vitamin B12 deficiency 1
Additional Recommendations
- Enteral nutrition should provide at least 2.5 mg cyanocobalamin per day in 1500 kcal, as recommended by the ESPEN micronutrient guideline 1
- Sublingual B12 formulations may be effective alternatives to oral tablets, but the most recent and highest quality study recommends hydroxocobalamin injections for replacement therapy 1
From the FDA Drug Label
Cyanocobalamin is indicated for vitamin B12 deficiencies due to malabsorption which may be associated with the following conditions: 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 (IM) is indicated for vitamin B12 replacement in cases of deficiency due to malabsorption. However, oral supplementation is usually sufficient for requirements in excess of normal due to certain conditions. 2
From the Research
B12 Replacement Therapy
- Vitamin B12 deficiency is a common condition that can be treated with replacement therapy, with various routes of administration available, including parenteral and oral routes 3.
- The effectiveness of oral administration of vitamin B12 has been compared to intramuscular administration in several studies, with high-dose oral vitamin B12 (1-2 mg daily) found to be as effective as intramuscular administration for correcting anemia and neurologic symptoms 4.
- A Cochrane review of randomized controlled trials found that high oral doses of vitamin B12 (1000 mcg and 2000 mcg) were as effective as intramuscular administration in achieving hematological and neurological responses 5.
Routes of Administration
- Intramuscular administration of vitamin B12 is a common treatment method, but it has some disadvantages, such as pain and relatively higher cost 6.
- Sublingual administration of vitamin B12 has been found to be as effective as intramuscular administration in correcting serum vitamin B12 levels and hematologic abnormalities in children and adults 6, 7.
- Oral administration of vitamin B12 is also effective, with high-dose oral vitamin B12 (1-2 mg daily) found to be as effective as intramuscular administration for correcting anemia and neurologic symptoms 4.
Dosage and Frequency
- The recommended dosage and frequency of vitamin B12 replacement therapy vary depending on the route of administration and the individual patient's needs 3, 4.
- For parenteral administration, a common regimen is 1000 micrograms of cyanocobalamin injected every 1-2 weeks for loading, and then once a month for maintenance 3.
- For oral administration, a daily dose of 1-2 mg of vitamin B12 is commonly recommended 4.