Treatment for Vitamin B12 Deficiency
The recommended treatment for confirmed vitamin B12 deficiency is hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks, followed by maintenance treatment with 1 mg intramuscularly every 2-3 months for life. 1, 2
Treatment Based on Clinical Presentation
Patients WITHOUT Neurological Involvement
- Administer hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks 1, 2
- Follow with maintenance treatment of 1 mg intramuscularly every 2-3 months for life 1, 2
Patients WITH Neurological Involvement
- Administer hydroxocobalamin 1 mg intramuscularly on alternate days until there is no further improvement 1, 2
- After improvement, transition to maintenance with hydroxocobalamin 1 mg intramuscularly every 2 months 2
- Seek urgent specialist advice from neurologist and haematologist if there is possible neurological involvement, such as unexplained sensory and/or motor and gait symptoms 1
Treatment Based on Cause of Deficiency
- For patients with malabsorption (including bariatric surgery patients), parenteral vitamin B12 is the recommended treatment and will be required for life 2, 3
- For patients with ileal resection (>20 cm of distal ileum), prophylactic vitamin B12 injections (1000 μg) monthly for life 2, 4
- For patients with pernicious anemia, parenteral vitamin B12 is the recommended treatment and will be required for life 5
Alternative Treatment Options
- Oral administration of high-dose vitamin B12 (1000-2000 mcg daily) can be considered as an alternative to intramuscular administration for patients without severe deficiency or neurological symptoms 4, 3, 6
- Oral supplementation has been shown to be equally effective in raising serum vitamin B12 levels as parenteral dosing in some studies 6
- However, for patients with malabsorption issues, parenteral administration remains the preferred method 2, 7
Important Considerations
- Do not give folic acid before treating vitamin B12 deficiency as it may mask underlying deficiency and precipitate subacute combined degeneration of the spinal cord 1, 2
- Check both vitamin B12 and folate levels, as folate deficiency may coexist 2
- Use either total B12 or active B12 as the initial test, and consider measuring methylmalonic acid to confirm deficiency in asymptomatic high-risk patients with low-normal levels of vitamin B12 2, 8
- Elderly patients have a higher risk of B12 deficiency, with metabolic B12 deficiency present in 18.1% of patients over 80 years 4
- Patients who have had bariatric surgery require close monitoring and supplementation 2, 3
Monitoring and Follow-up
- After initiating treatment, monitor clinical response and hematologic values 5
- For patients with pernicious anemia, once hematologic values have normalized, continue with 100 mcg monthly for life 5
- Clinical response to treatment may vary considerably between individuals, and some patients may require more frequent administration to remain symptom-free 7
- Titration based solely on measuring biomarkers such as serum B12 or methylmalonic acid is not recommended; clinical response should guide treatment 7