Chapter 6-13: Underproduction Anemias (framed using Mean Corpuscular Volume [MCV])

Microcytic anemias (MCV < 80 mcm³)

1. Iron deficiency

2. Thalassemia

3. Anemia of inflammation/chronic disease (more often normocytic)

4. Sideroblastic anemia (congenital, lead exposure, medications)—rare

5. Copper deficiency or zinc poisoning—rare

Macrocytic anemias (MCV > 100 mcm³)

1. Megaloblastic anemias (due to abnormalities in DNA synthesis; hypersegmented neutrophils also occur)

   1. Vitamin B₁₂ deficiency

   2. Folate deficiency

   3. Antimetabolite drugs, such as methotrexate or zidovudine

2. Nonmegaloblastic anemias (no hypersegmented neutrophils)

   1. Alcohol abuse

   2. Liver disease

   3. Hypothyroidism

   4. Myelodysplastic syndrome (often causes pancytopenia)

Normocytic anemias

1. Anemia of inflammation/chronic disease (chronic kidney disease, infection, inflammation, malignancy, aging)

2. Early iron deficiency

3. Bone marrow suppression

   1. Invasion by malignancy or granulomas

   2. Acquired pure red cell aplasia (parvovirus B19, HIV, medications [mycophenolate mofetil, trimethoprim-sulfamethoxazole, phenytoin, recombinant human erythropoietins], thymoma, other malignancies, immune disorders)

   3. Aplastic anemia (often causes pancytopenia)

4. Endocrine (hypopituitarism or hypothyroidism)