Why Vitamin B12 Deficiency Should be on your Radar Screen

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<strong>Vitamin</strong> <strong>B12</strong> <strong>Deficiency</strong> Managing Patients With Evidence of a <strong>Vitamin</strong> <strong>B12</strong> <strong>Deficiency</strong> “A caregiver must manage a subclinically deficient patient with pernicious anemia as a cause quite differently and pay closer attention than to a similar patient without it.” Carmel, 2006 Clinical <strong>Vitamin</strong> <strong>B12</strong> <strong>Deficiency</strong> Options available for treating a clinical vitamin <strong>B12</strong> deficiency include oral and parenteral (intramuscular or subcutaneous) preparations. Intravenous dosing is not recommended <strong>be</strong>cause this will result in most of the vitamin <strong>be</strong>ing lost in the urine.(74) The response of a patient with vitamin <strong>B12</strong> deficiency anemia to treatment is usually rapid, with reticulocytosis occurring within 2–5 days, and the hematocrit normalizing within weeks.(10) Treatment with cobalamin effectively halts progression of the deficiency process, but might not fully reverse more advanced neurologic effects.(39, 42) If the underlying cause of the vitamin <strong>B12</strong> deficiency is treatable (e.g., fish tapeworm infection or bacterial overgrowth), then treatment should include addressing the underlying etiology.(7) <strong>Vitamin</strong> <strong>B12</strong> is considered safe, even at levels much higher than the recommended dose. It has not <strong>be</strong>en shown to <strong>be</strong> toxic or cause cancer, birth defects, or mutations.(10, 75) Be aware, however, that patients who have a vitamin <strong>B12</strong> deficiency with associated megaloblastic anemia might experience hypokalemia and fluid overload early in treatment due to increased erythropoiesis, cellular uptake of potassium, and increased blood volume.(76, 77) While the route, dosage, treatment timing, and follow-up might vary somewhat, there is no question about the decision to treat patients with pernicious anemia or with a low serum <strong>B12</strong> level and hematologic or neurologic signs or symptoms without pernicious anemia (clinical 35 Cobalamin replacement is effective <strong>be</strong>cause crystalline forms of <strong>B12</strong> can <strong>be</strong> absor<strong>be</strong>d even when animal protein-bound forms cannot <strong>be</strong> digested. <strong>Vitamin</strong> <strong>B12</strong> is not carcinogenic, teratogenic, or mutagenic. It is considered safe even at 1,000 times the RDA. Baik and Russell, 1999
<strong>Vitamin</strong> <strong>B12</strong> <strong>Deficiency</strong> vitamin <strong>B12</strong> deficiency). Once treated for a vitamin <strong>B12</strong> deficiency due to pernicious anemia or other irreversible severe problems with absorption, patients need to continue some form of cobalamin therapy for life.(7) Parenteral (Intramuscular or Subcutaneous) Administration of parenteral crystalline cobalamin has <strong>be</strong>en the standard treatment protocol for vitamin <strong>B12</strong> deficiency for decades.(78, 79) Few side effects have <strong>be</strong>en reported, and patient acceptance is generally high. Anecdotally, the subcutaneous route causes less burning than does the intramuscular route (Carmel RA. New York Methodist Hospital [personal communication] 2006- 2007). Regimens for parenteral administration vary. An approach suggested by Stabler and Allen is 1 milligram (mg) (or 1,000 micrograms [µg]) of vitamin <strong>B12</strong> given weekly for 8 weeks, then once monthly for life.(7) Some providers have used quarterly injections after the initial dosing protocol. However, experts state that in pernicious anemia or severe malabsorptive deficiency quarterly injections are not sufficient, noting that cobalamin levels start to fall prior to the 1 month followup (Allen RH. University of Colorado [personal communication] 2006 -2007). Oral Large, daily oral replacement doses might <strong>be</strong> an acceptable alternative if patients are compliant.(7) Sufficient amounts of vitamin <strong>B12</strong> are absor<strong>be</strong>d via passive diffusion in the small intestine.(2, 11) A study by Eussen et al. demonstrated a linear response in the reduction of metabolites and increased serum <strong>B12</strong> levels with increasing dosages of oral cyanocobalamin.(80) A common therapy is 1 mg (1,000 µg) of vitamin <strong>B12</strong> to <strong>be</strong> consumed daily.(2, 11, 14) Intranasal A relatively new vehicle for vitamin <strong>B12</strong> therapy is a cyanocobalamin gel for intranasal use. Some experts are not convinced of its efficacy, and the cost is $30 for 36
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Why Vitamin B12 Deficiency Should be on your Radar Screen

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