Macrocytosis - DDx

Differential diagnosis of macrocytosis:

a) Megaloblastic anemia (impaired DNA synthesis) secondary to B12/folate deficiency or antimetabolite therapy

b) MDS

c) Hypothyroidism

d) Liver disease (possibly from lipid deposition into RBC membrane)

e) EtOH

f) Reticulocytosis: reticulocytes are larger than mature RBCs --> RDW should be increased

(Christopher Woo MD, 6/22/10)