Macrocytic anemia

Background

• Anemia with elevated mean corpuscular volume (MCV) above 100 fL

Etiologies

• Megaloblastic (hypersegmented neutrophils suggesting impaired DNA synthesis)
  • Vitamin B12 deficiency
  • Folate deficiency
  • Methotrexate effect
  • Myelodysplastic syndrome
• Non-megaloblastic
  • Alcohol consumption
  • Hereditary spherocytosis
  • Hypothyroidism
  • Liver disease
  • Reticulocytosis from bleeding or hemolysis
• May be seen in infants, patients with Down syndrome, and pregnant women
• Extreme macrocytosis greater than 130 fL is sometimes seen with zidovudine, stavudine, and lamivudine