Vitamin B12 deficiency may be treated with either intramuscular (IM) injection or high does oral formulations. There are fewer data available about the efficacy of nasal gels or sublingual preparations of B12. An effective initial paranteral treatment in the patient with severe clinical abnomalities is vitamin 12 1000 mg IM daily if the patient is hospitalized with severe anemia, then weekly for approximately eight weeks. Subjects with severe demyelinating disease of the spinal cord may benefit by having weekly or biweekly B12 injections for up to six months. Stable patients can then receive 1000 mg IM per month. Approximately 10 to 20 percent of patients with severe mal abosrption of B12 will not have normal serum MMA with injections spaced at four weeks, however. The injections can often be accomplished by family members, etc, so that the patient does not need monthly visits to a healthcare facility.
A high dose oral B12 randomized trial showed higher serum B12 values and lower MMA values at four months. In addition, high dose vitamin B12 tablets, usually 1000mg per day, have been used in Sweden for 40 years with great success. Thus a resonable alternative to injections is 1000- 2000 mg orally daily. It is controversial whether the patient is better served by IM or oral replacement. An advantage of parenteral treatment is that the paitent remains under observation and thus there will be better compliance with treatment. The opponents of the parenteral approach note that Vitamin B 12 replacement is incorrectly discontinued by physicians frequently and or that changing medical providers may cause lapses in treatment. In addition, IM injections are painful and cause bleeding in very frail, debilitated individuals. An advantage of oral treatment is that the high dose tablets are obtainable from all grocery stores and pharmacies without a prescription so the patient will always have access to the therapy.
Ironically, the cost of the daily tablets is considerably higher than self administrated injections or those obtained at a medical facility for most senior patients. There may also be problems with the bio availability of some preparations, and food decreases absorption. Daily therapy in a patient who may be taking 5-10 other medications may also be a problem. The common lay perception that vitamins are an optional therapy could also be dangerous in the patient with pernicious anemia, since cessation of therapy will eventually cause relapse of the original clinical syndrome within six moths to two years. Complete correction of anemia can be expected if adequate erythropoietin and iron are available. However, mixed anemia’s are to be expected in seniors and it is not uncommon that the primary marrow disorders coexist with mild B12 deficiency. Patients with pretreatment serum MMA 500-1000 nmol/L rarely have correction of anemia since there is usually an additional underlying cause. Likewise, only neurological symptoms due to B 12 deficiency will respond. In contrast, MMA and homocysteine will correct often dropping into the low normal range.