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Switching to oral vitamin [B.sub.12] replacement.

The Problem

You are an attending in a local nursing home and you have several elderly residents who receive monthly intramuscular injections of vitamin [B.sub.12]. The nursing home pharmacist tells you that vitamin [B.sub.12] replacement can be achieved with oral replacement at a significantly lower cost to the nursing home. You had been taught that [B.sub.12] replacement should be administered intramuscularly for patients with pernicious anemia or intestinal disorders, and you have practiced this way, but you decide to review the evidence.

The Question

In elderly patients requiring vitamin [B.sub.12] replacement, can adequate [B.sub.12] replacement be achieved with oral [B.sub.12] supplements?

The Search

You go to PubMed ( and enter "cobalamin" AND "oral" AND "intramuscular," limiting the search to randomized controlled trials.

Our Critique

This study was not blinded, but hematologic and biochemical verification was used to monitor treatment response. In addition, the patients' concomitant medications were recorded. This study provides excellent evidence that an oral replacement route for [B.sub.12] is effective. A recent systematic review combined this study with another similar study (108 total patients combined) and concluded that oral and intramuscular (IM) [B.sub.12] replacement have similar effectiveness. An editorial that accompanied the systematic review noted that the most readily available dose of [B.sub.12] is 500 mcg, so patients might have to take four pills. Administration of oral [B.sub.12] might be ideal in some settings, such as for the homebound patient living alone. However, an important additional consideration is that oral [B.sub.12] might not be included in formularies and thus would incur out-of-pocket expenses for patients.

Clinical Decision

Over the next several months, you decide to review the patients who are on maintenance or replacement therapy for [B.sub.12] with IM injections and you plan to consider oral replacement, while taking into consideration the constraints of the health care system.

A.M. Kuzminski, et al.

Effective treatment of cobalamin deficiency with oral cobalamin (Blood 1998;92:1191-8).

* Subjects and Design: In this randomized, controlled, single-site clinical trial, the subjects were recruited from four ambulatory care centers in New York State. Potential subjects were eligible for enrollment in the study if they had serum cobalamin (vitamin [B.sub.12]) levels less than 160 pg/mL with confirmation of low cobalamin in another specimen, and if they had an elevated serum methylmalonic acid (MMA) level, an elevated serum total homocysteine level, or elevations in both metabolites greater than three standard deviations above the normal mean.

* Intervention: Subjects received either cyanocobalamin 2 mg (two 1,000-mcg tablets) orally with breakfast for 120 days, or cyanocobalamin as 1-mg IM injections on days 1, 3, 7, 10, 14, 21, 30, 60, and 90.

* Outcomes: The effectiveness of oral cyanocobalamin treatment was evaluated by measuring hematologic and neurologic improvement, as well as changes in serum concentrations of cobalamin, MMA, and homocysteine. In the oral [B.sub.12] group, all of the serum cobalamin concentrations were obtained more than 24 hours after the last oral dose. In the IM group, serum was obtained 9 days after the last of a series of six 1-mg injections, with the subsequent 2- and 4-month samples collected 1 month after the most recent 1-mg maintenance injection. MMA is a metabolite that is frequently abnormal before serum cobalamin levels become subnormal. Also, total homocysteine levels are frequently elevated in the setting of vitamin [B.sub.12] deficiency.

* Results: A total of 38 patients were randomized, with 18 assigned to oral vitamin [B.sub.12] therapy and 15 assigned to IM injections (the other 5 patients were found to have folate deficiency). The subjects in the two groups were similar at baseline with respect to mean age, hematocrit, mean corpuscular volume, serum cobalamin, folate, MMA, and total homocysteine. The etiology of their [B.sub.12] deficiency was related to pernicious anemia, gastrointestinal surgery, atrophic gastritis, poor protein intake, or medications. In both groups, a decrease in MCV was observed, and four patients in each group experienced dramatic improvements in neurologic findings, specifically mental status, gait, and vibratory sense. Serum cobalamin levels were significantly higher in the oral group than in the parenteral group at 2 months (643 [+ or -] 328 vs. 306 [+ or -] 118 pg/mL; P < .001) and at 4 months (1,005 [+ or -] 595 vs. 325 [+ or -] 165 pg/mL; P < .0005). At 4 months, serum levels of cobalamin were greater than 300 pg/mL in one-half of the parenteral group, compared with all of the subjects in the oral group. Also at 4 months, the mean MMA and homocysteine levels were 169 nmol/L and 10.6 [micro]mol/L, respectively, in the oral group and 265 nmol/L and 12.2 [micro]mol/L, respectively, in the parenteral group. These differences between the two groups were significant (P < .0005 and P < .05, respectively).


DR. EBBERT and DR. TANGALOS are with the Mayo Clinic in Rochester, Minn. To respond to this column or suggest topics for consideration, write to Dr. Ebbert and Dr. Tangalos at our editorial offices or
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Article Details
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Author:Ebbert, Jon O.; Tangalos, Eric G.
Publication:Internal Medicine News
Article Type:Clinical report
Geographic Code:1USA
Date:Sep 15, 2006
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