Macrocytosis

Definition:

Macrocytosis is the frequent occurrence of macrocytes. These are erythrocytes with a diameter of more than 9 µm and a MCV < fl. Oval macrocytes are typically found in megaloblastic anemia.

Occurrence:
Macrocytosis occurs when abnormal erythropoiesis is present as in alcohol consumption, liver disease, during use of cytotoxic (e.g. azathioprine, hydroxyurea) or virostatic drugs (e.g. zidovudine), in megaloblastic anemia through a vitamin B₁₂ and/or folic acid deficiency as well as in myelodysplastic syndromes.