eMedicine Specialties > Hematology > Red Blood Cells and Disorders

Pernicious Anemia: Treatment & Medication

Author: Marcel E Conrad, MD, (Retired) Distinguished Professor of Medicine, University of South Alabama
Contributor Information and Disclosures

Updated: Aug 26, 2009

Treatment

Medical Care

• The following goals are the most important in establishing care for these patients:
  • To establish that the patient has Cbl deficiency
  • To determine the cause of the failure to absorb Cbl (A controversy in the field exists; not all hematologists work to establish a precise cause for low vitamin B-12 levels. The nuclear medicine tests are expensive and cumbersome and many simply treat patients if a differential diagnosis of a low–vitamin B-12 state is established.)
  • To treat the patient with adequate doses of Cbl
  • To confirm the diagnosis by documenting that specific therapy is effective
  • To ensure administration of adequate quantities of Cbl for the lifespan of the patient
• Blood transfusions: Transfusions are rarely required in patients with a megaloblastic anemia due to vitamin B-12 deficiency. The likelihood of obtaining a dramatic response to therapy within a few days of initiating treatment makes it unnecessary to subject the patient to the hazards of blood transfusion. Usually, mild-to-moderate congestive heart failure secondary to anemia abates with bed rest and low-dosage diuretic therapy. However, if the congestive heart failure is severe and/or the patient has coronary insufficiency, a transfusion of packed red blood cells may be necessary. Transfuse the blood slowly because patients who are transfused for severe anemia often develop circulatory overload. For this reason, low-dose diuretic therapy is often employed with transfusion.

Consultations

A consultation with a neurologist may be desirable in patients with unusual neurological manifestations. This is most useful in patients without a macrocytic megaloblastic anemia.

Diet

People who are strict vegetarians and, most particularly, people who do not consume eggs, milk, or meat can develop Cbl deficiency. Counsel these people to either change their dietary habits or remain on supplementary vitamin B-12 therapy for their lifetime. An oral tablet of 100-200 mcg taken weekly should provide adequate therapy.

Activity

Curtail strenuous physical activity in patients with severe anemia until they develop an adequate hematological response following treatment.

Medication

Vitamin B-12 is available for therapeutic use parenterally as either cyanocobalamin or hydroxocobalamin.⁴ Both are equally useful in the treatment of vitamin B-12 deficiency, and they are nontoxic (except for rare allergic reactions). Theoretical advantages exist to using hydroxocobalamin because it is retained better in the body and is more available to cells; both chemical forms of Cbl provide prompt correction. Cbl is available in a solution for injection in 100- to 1000-mcg/mL dosages.

Most of the injected doses in excess of 50 mcg rapidly are excreted in the urine. Thus, when starting therapy, repeated doses are recommended in order to replenish body stores. A number of regimens have been recommended. One regimen is daily SC administration for the first week. If significant reticulocytosis provides documentation of the success of therapy, then doses are administered twice weekly for another 4-5 weeks. Then, 100 mcg can be administered monthly. Alternatively, others have advocated weekly injections of 1000 mcg of vitamin B-12 for 5-6 weeks, followed by monthly injections.

Limited studies have shown that adequate therapy can be maintained after the initial parenteral loading doses by ingestion of 250-1000 mcg of vitamin B-12 PO daily because, even with a total absence of IF, about 1% of a PO dose is absorbed and the daily requirement for vitamin B-12 is 1 mcg/d. This route may be necessary in patients who have allergic reactions to parenteral administration (rare). If the PO route is used, obtain serum Cbl measurements at periodic intervals to ensure that adequate quantities of Cbl have been absorbed.

Vitamins

Cbl is an essential vitamin. The inability to absorb adequate quantities of the vitamin from the diet leads to hematological and neurological complications.

Cyanocobalamin (Crystamine, Cyomin)

Deoxyadenosylcobalamin and hydroxocobalamin are active forms of vitamin B-12 in humans. Microbes, but not humans or plants, synthesize vitamin B-12. Vitamin B-12 deficiency may result from IF deficiency (pernicious anemia), partial or total gastrectomy, or diseases of the distal ileum.
May be administered IM/SC. At the initiation of therapy, large daily doses are administered in order to replenish body stores with Cbl.
With certain hereditary defects of Cbl, metabolism doses of Cbl (eg, 1000 mcg SC qwk) may be required to obtain a response.

Multivitamins (MVI-12, Cernevit-12)

Used as dietary supplement.

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