Vitamin B12 and the Production of Polycythemia by Cobalt

Abstract

The daily subcutaneous administration of vitamin B₁₂ in a dosage of 3 µg per day for 6 weeks, then at a dosage of 10 µg per day for two weeks longer, did not produce a significant increase in hemopoiesis in the normal rat as measured by the concentration of hemoglobin in the blood. The daily parenteral administration of cobalt produced the characteristic polycythemia without increasing the vitamin B₁₂ content of the liver, although there was some increase in the vitamin B₁₂ content of the feces. These results are interpreted as evidence that cobalt does not produce a polycythemia by way of the intermediary formation of vitamin B₁₂.