Excretion,Enterohepatic Circulation,and Retention of Radiovitamin B 12 in Pernicious Anemia and in Controls. ∗

Summary

1) After parenteral administration of radiovit. B₁₂, radioactivity reaches the gut mainly with the bile, but other components of duodenal juice also contain radioactivity. 2) The calculated daily biliary excretion of radioactivity in controls is invariably larger than daily fecal excretion, suggesting enterohepatic circulation. In cases with defective B₁₂-absorption, there are indications of an enterohepatic circulation in only about half of the cases. 3) A higher percentage of radio-vitamin administered is retained in serum, and a numerically lower percentage is excreted/day in urine, bile, and feces of patients with B₁₂-avitaminosis than in controls. These facts suggest that more B₁₂ is retained in states of deficiency.