Selective vitamin B12 malabsorption without anaemia but with profound failure to thrive.
A 7-month-old boy presented with vomiting and failure to thrive associated with proteinuria, methylmalonic aciduria and macrocytosis, but without anaemia. Plasma vitamin B12 levels were normal by a radio-dilution method. He was treated as an inborn error of metabolism with intramuscular cyanocobalamin and a low protein diet. However when treatment was withdrawn he remained well for 11 months before relapsing with vomiting and weight loss. Re-investigation again showed methylmalonic aciduria, but the haemoglobin was low and plasma vitamin B12 levels by a specific method showed them to be reduced. Studies of vitamin B12 absorption showed the picture of selective malabsorption. He was started on regular cyanocobalamin injections.
D002675:Child, Preschool; D004044:Dietary Proteins / Q000627:therapeutic use; D006801:Humans; D007223:Infant; D008286:Malabsorption Syndromes / Q000175:diagnosis* / Q000628:therapy; D008297:Male; D008764:Methylmalonic Acid / Q000652:urine; D011507:Proteinuria; D014805:Vitamin B 12 / Q000378:metabolism* / Q000627:therapeutic use
D004044:Dietary Proteins; D008764:Methylmalonic Acid; D014805:Vitamin B 12