IN A CASE of hereditary spherocytosis, complicated by severe megaloblastic anemia, the patient failed to respond to massive doses of cyanocobalamin (vitamin B₁₂) given parenterally but did respond rapidly to minute oral doses of folic acid. These last observations cast some doubt upon the ability of cyanocobalamin to affect megaloblastic anemias due to folic acid deficiency.

Report of a CaseÌý A 45-year-old Irish housewife was admitted to the psychiatric division of St. Vincent's Hospital on June 26, 1963, complaining of weakness, fatigue, anorexia, pain in the tongue, palpitations, dyspnea, and ankle edema, all of about three weeks' duration.She was first seen in this hospital in March 1959, when the diagnosis of hereditary spherocytosis was made on the basis of splenomegaly, reticulocytosis (6.8%), spherocytosis of the red blood cells, normoblastic hyperplasia of the bone marrow, and increased hypotonic fragility (Fig 1). At that time the patient was not significantly