Vitamin B12 (cobalamin) deficiency is uncommon in infancy. It may be associated with (1) inadequate dietary intake (eg, breast-fed infants of strict vegetarian [vegan] mothers); (2) congenital defects in intestinal absorption and transportation (eg, absence or malfunction of gastric intrinsic factor, selective ileal transport defect, or transcobalamin II deficiency); or (3) defects in intracellular processing.1,2 The main clinical feature of vitamin B12 deficiency is megaloblastic anemia. We herein describe a female infant who presented with developmental delay at 12 months. She was recognized to have macrocytic anemia and methylmalonicaciduria associated with vitamin B12 deficiency. Her anemia and developmental status improved after parenteral administration of cyanocobalamin. It appears that this deficiency developed after she was exclusively breast-fed by a mother with inadequate breast-milk vitamin B12 levels secondary to gastric bypass surgery and a semivegetarian diet.
Report of a Patient.
A 12-month-old female infant was referred for