Oral or parenteral therapy for vitamin B12 deficiency

Abstract

M Elia's commentary1Elia M Oral or parenteral therapy for vitamin B12 deficiency.Lancet. 1998; 352: 1721-1722Summary Full Text Full Text PDF PubMed Scopus (98) Google Scholar reviews the use of parenteral and oral vitamin B12 preparations; but does not discuss the rare but difficult management of hypersensitivity to these preparations. We report the case of a 73-year-old woman who presented to our department in 1992 with a macrocytic anaemia and a reduced serum concentration of vitamin B12 of 109 ng/mL (normal range 170-740 ng/mL). Other haematinic concentrations were normal and she was positive for antigastric parietal cell antibodies, but negative for antigastric intrinsic factor antibodies. Treatment with intramuscular hydroxocobalamin 1000 μg was started; 14 h after the injection, she became flushed and developed facial swelling. Subsequent treatment with one 50 μg tablet of cyanocobalamin was followed by general malaise, facial flushing and swelling, vomiting, and hypertension, within 2-3 h and at 6 h she had developed an extensive, weeping dermatitic eruption affecting her face. She was treated with intravenous chlorpheniramine and intravenous and topical corticosteroids. Skin patch testing confirmed sensitivity to common allergens but not to colbalt. Bone marrow and cytogenetic studies done after treatment with vitamin B12 excluded myelodysplastic syndrome. The initial treatment with intramuscular and oral vitamin B12 was sufficient to maintain normal serum concentration until early 1995, when it fell to 139 ng/L. She was subsequently managed with intermittent blood transfusion that was also temporarily successful in restoring her serum vitamin B12 to within normal range and correcting the macrocytic anaemia to varying degrees. However, by early 1998, this approach had become ineffective and her serum vitamin B12 had fallen to 100 ng/L. In view of anaemia and potential neurological difficulties, a decision was made to treat her with intramuscular hydroxocobalamin with corticosteroid and antihistamine cover. On the intensive-care unit, she received a test dose of 100 μg after premedication with intravenous hydrocortisone 200 mg, chlorpheniramine 10 mg and ranitidine 150 mg. The absence of a reaction made possible the administration of a full therapeutic dose of intramuscular hydroxocobalamin 1000 μg. Subsequently, the serum vitamin B12 increased to within the normal range and the macrocytic anaemia has resolved. Hypersensitivity reactions to vitamin B12 preparations2Denis R Amin S Cummins D Sensitivity reaction to parenteral vitamin B12: recurrence of symptoms after Marmite ingestion.Clin Lab Haemat. 1996; 18: 129-131Crossref PubMed Scopus (3) Google Scholar are rarely documented and range from urticarial and dermatitic rashes to circulatory collapse and death. A sensitivity to parenteral and oral preparation has been previously reported, and there is also a report of a sensitised patient reacting to Marmite, which is fortified with cyanocobalamin. Our patient is the first report of successful prevention of vitamin B12 hypersensitivity. We suggest that such patients might be managed similarly with premedication with hydrocortisone and antihistamine and close overnight inpatient observation.