Agewise Differences in the Urinary Excretion of Vitamin B12 Following Intramuscular Administration

Abstract

The urinary excretion of vitamin B₁₂ following its intramuscular administration in crystalline form was studied at 20, 30, 50 and 75 µg dose levels in groups of male subjects, aggregating 107 individuals in widely separated age categories. In study I, a young group averaging 29.7 years excreted significantly more B₁₂ than did an old group averaging 76.4 years. In study II, an orderly and significant decrement in B₁₂ excretion was observed from young (28.0 years) to middle (61.4 years) to old (81.6 years) groups. The decrement in B₁₂ excretion with age parallels decrements in renal function with age. However, so small a fraction of administered B₁₂ appears in the urine that the observed differences cannot be attributed to renal factors alone.