The treatment of pernicious anemia is usually straight-forward. However, anaphylactic reactions after injection of vitamin B
12 preparation have been described in the past. This is a case report of pernicious anemia in which adverse reactions occurred soon after vitamin B
12 injection as manifested by marked neutropenia and severe impairment of liver functions terminating in death.
An 79-year-old man with no significant past illness or history of allergy to drugs was admitted on November 26, 1982 for investigation of anemia. Peripheral blood on admission showed RBC 213×10
4/mm
3, Hb 8.7g/d
l, WBC 4,700/mm
3 with almost normal differential, and platelet 5.5×10/mm. Bone marrow aspiration revealed erythriod hyperplasia with megaloblastic changes. The serum B
12 was 220pg/m
l. The diagnosis of pernicious anemia was confirmed by the Schilling test and the presence of intrinsic factor antibodies. About 2 hours after receiving an intramuscular injection of cobamide (Calomide S) 1,000 μg for the first time, severe allergic reactions with a high fever and general skin eruptions developed followed by elevation of transaminases, hyperbilirubinemia and marked granulocytopenia 3 days later. Subsequently, prednisolone 60mg per day was started, and over the next 2 days WBC count gradually returned to normal. However, because of long-lasting high fever despite discontinuation of vitamin B
12 therapy, antibiotics were given with a suspicion of complicating sepsis, with which return of a marked granulocytopenia and worsening of hepatic dysfunction occurred in 2 days. His condition continued to deteriorate with disturbances of consciousness, and he died due to respiratory distress 11 days after injection of vitamin B
12.
This patient was thought to have sensitivity not only to vitamin B
12 but also to antibiotics. At present, it is not clear whether allergic reactions were due to substances added to the drugs as a preservative or to vitamin B
12 itself. It is important, however, to be aware of such rare but potentially lethal side effects.
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