Studies of a Patient with Selective Deficiency in Absorption of Vitamin B₁₂

A 2 year old girl with a megaloblastic anemia secondary to B₁₂ deficiency was presented. The mechanism appeared to be a specific inability to absorb vitamin B₁₂ from the small bowel in the absence of any other functional disability.

Evidence of absorption of vitamin B₁₂ was obtained when intestinal juice from a normal patient was administered with the test dose of vitamin B₁₂. This evidence consisted of (1) an increased urinary excretion of the test dose (positive Schilling test), (2) a decreased fecal excretion of the labelled B₁₂ and (3) the presence of significant counts over the liver (positive Glass test).

A generalized malabsorption can only be totally and absolutely disproven by testing over many years. It is considered more probable, however, that this patient lacks an intestinal factor required for the absorption of vitamin B₁₂.