Vitamin B12 Absorption Tests

Abstract

Eighty-two patients who underwent gastrectomy were investigated for vitamin B₁₂deficiency 1 to 22 years after surgery. Serum vitamin B₁₂levels were found to be abnormally low in 62. Red blood cell (RBC) B₁₂levels were determined in 22 patients with decreased serum B₁₂levels, and were found to be low in 21, demonstrating a true tissue deficiency of the vitamin. More than two thirds of the patients with subnormal serum B₁₂levels had normal absorption by the Schilling and the plasma B₁₂absorption methods. It is reasoned that most such patients have difficulty in absorbing the protein-bound food B₁₂and not the crystalline B₁₂used in various B₁₂absorption tests. The latter therefore seem to have very little value in the follow-up of partial gastrectomy. Serum or RBC B₁₂determinations are suggested for this purpose, instead.