Low Vitamin B₁₂ Concentrations in Serum in Fish Tapeworm Anæmia

Abstract

VARIOUS communications have been published on the microbiological vitamin B₁₂ activity in the sera from both healthy persons and patients suffering from various diseases. The concentration of vitamin B₁₂ varies fairly considerably in normal people. The lower limit is 70–100 µµgm. and the upper 420–900 µµgm. vitamin B₁₂/ml. of serum, depending on the microbiological method employed. Very low values, usually less than 50 µµgm./ml., have been found in pernicious anæmia¹.