Macrocytic and marrow failure anemias

Abstract

Anemias from marrow failure may result from absent or ineffective production of RBCs. These anemias are frequently characterized by the presence of macrocytic cells, in which the mean corpuscular volume is > 100 fL or a subpopulation of RBCs is abnormally large. The most common and important causes of macrocytic anemias, because they are treatable, are vitamin B12 and folate deficiencies. Identification of the cause of a macrocytic anemia therefore generally depends on confirmation of these vitamin deficiencies by direct measurement of their concentration in blood, or of substances that accumulate in such deficiencies. Other laboratory tests are performed as needed if vitamin B12 and folate deficiencies are excluded.