Abstract

Vitamin B₁₂ levels in erythrocytes were low in untreated hypochromic anaemia, rose to abnormally high levels during therapy with iron alone, and finally slowly fell to normal. These changes were similar to those previously found in pernicious anaemia in response to vitamin B₁₂ therapy and in folate-deficiency anaemia in response to folic acid, thus changes in erythrocyte B₁₂ levels are not always due directly to changes in B₁₂ metabolism but may be secondary to changes in the levels of other haematinic factors.