V. Herbert, M.D.
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The 200 to 900 picograms of vitamin B12 normally present per ml of plasma are bound mainly to an alpha globulin. Normally, this vitamin B12 binding protein is almost saturated; in vitamin B12 deficiency states, it is mainly unsaturated. Were it a transport protein functionally like transferrin, it should take up and deliver a tracer dose of vitamin B12 to tissues in proportion to its unoccupied binding capacity. In fact, less of an intravenously administered tracer dose of vitamin B12 leaves the serum of patients with vitamin B12 deficiency than that of normal subjects. In vitro, some vitamin B12 is
Herbert V. Plasma Vitamin B12 Binding Protein.. Ann Intern Med. 1963;58:730. doi: https://doi.org/10.7326/0003-4819-58-4-730_2
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Published: Ann Intern Med. 1963;58(4):730.
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