Vit. B 12 Levels in Serum and Urine Following Parenteral Administration of Crystalline Vit. B 12 or Liver Extract. ∗

Summary

Liver extract and crystalline vit. B₁₂ were administered in equivalent amounts to 2 groups of normal subjects, and total serum vit. B₁₂ levels, bound vit. B₁₂ levels, and urinary excretion of vit. B₁₂ compared in the 2 groups. Concentration of free vit. B₁₂ was higher in the group receiving crystalline vitamin. Over the 24-hour period, percentage of bound vitamin serum was greater in the group receiving liver extract. Urinary excretion of vit. B₁₂ was significantly lower in the group receiving liver extract.