Table 1.

Physiological conditions that lead to alteration of RDW values.

RDW values	Normal	Elevated
Decreased MCV	(i) Anemia of chronic disease (ii) Hemoglobin E trait (iii) Heterozygous thalassemia	(i) Iron deficiency (ii) HbS/Beta thalassemia (iii) Hemolytic anemia (iv) Microangiopathic hemolytic anemia
Elevated MCV	(i) Chronic liver disease (ii) Aplastic anemia (iii) Chemotherapy/antivirals/alcohol	(i) Vitamin B12, folate deficiency (ii) Immune hemolytic anemia (iii) Hereditary spherocytosis
Normal MCV	(i) Anemia of chronic disease (ii) Acute blood loss or hemolysis	(i) Early vitamin B12, folate deficiency (ii) Sickle cell anemia (iii) Transfusions (iv) Chronic hepatobiliary disease