Demonstration of vitamin B12 deficiency by a simple cytochemical reaction in the peripheral blood smear

Summary A simple, rapid and inexpensive cytochemical method for the detection of vitamin B 12 deficiency was applied in several types of anemias and matched with the levels of vitamin B 12 and folic acid in the serum of the patients. It was found that in patients with low vitamin B 12 levels the stained erythrocytes and the erythroid precursors showed a yellowish brown discoloration, which was not detected in folic acid deficiency and all other types of anemias. This test therefore may be used for differentiation between B 12 and folate deficiency whenever megaloblastic anemia is diagnosed.