American Journal of Clinical Nutrition, Vol 21, 665-672, Copyright © 1968 by The American Society for Clinical Nutrition, Inc.

Whole-Body Counting Studies of Retention and Accessibility of Radioactive Vitamin B₁₂

¹ From Medical Research Center, Brookhaven National Laboratory, Upton, New York

1) The rate of disappearance of ⁶⁰Co-cyanocobalamin (CNCB) from the body as measured by whole-body counting was found to change continuously as a function of time after administration.

2) The administration of large doses of vitamin B₁₂ (500-1,000 µg) any time after ⁶⁰Co-CNCB administration caused the biologic T of ⁶⁰Co-CNCB to decrease.

3) The administration of small doses (100 µg) of vitamin B₁₂ caused no detectable change in biologic T of ⁶⁰Co-CNCB.

4) The administration of large doses of CNCB caused a decreased biologic T of ⁵⁸Co-hydroxocobalamin (HOCB) and the administration of large doses of HOCB caused a decreased biologic T of ⁶⁰Co-CNCB, and both analogues had similar biologic T's over the study period.