#19 Vitamin B12 Deficiency: Monthly shots or daily pills?
Reading Tools for Practice Article can earn you MainPro+ CreditsJoin Now
Already a CFPCLearn Member? Log in
- The first study2 randomized 38 outpatients to daily oral B12 at 2000 mcg/day or IM B12 1000 mcg at days 1, 3, 7, 10, 14, 21, 30, 60, 90.
- The second study3 randomized 70 patients to 1000 mcg B12 oral or IM: Daily for 10 days, then weekly for one month and then monthly for three months.
- Over 3-4 months of follow-up, both trials showed oral B12 as effective as IM therapy1 in:
- B12 levels and associated biochemical B12 markers (total homocysteine and serum methylmalonic acid)
- Hematological and neurological responses.
- A trial published since the meta-analysis also found similar efficacy between a novel B12 formulation and IM for B12 levels.4
- All trials had important limitations: Small,2-4 short,2-4 unblinded,2-4 and lack of intention to treat analysis,2,3 and/or written/funded by the manufacturer.4
- 5-20% of elderly patients are B12 deficient.5
- The majority of Canadian physicians use IM B12 in treating deficiency.6
- Switching from IM to oral B12 would reduce health care costs as well as the discomfort and inconvenience of intramuscular injections.7
- Oral B12 appears effective over a range of causes of B12 deficiency (dietary, pernicious anemia, gastric or ileal surgery, malabsorption syndromes) studied.2,3,8,9
- Celiac Disease and Inflammatory Bowel Disease are not well studied.
- Due to limitations in the evidence, patients switched to oral should likely have their B12 levels checked to confirm they are not declining.10
- Dosing recommendation varied between included RCTs, so a simple recommendation is difficult;2,3
- A well designed Canadian cohort study demonstrated that 1 mg/day is effective.8
- However, first two RCTs used frequency over time so dosing frequency can be reduced with monitoring, if levels are normal and stable.