Definition

• MCV 80-100

• Hemolytic anemia
• Microcytic anemia
• Macrocytic anemia
• Aplastic anemia
• Anemia, general approach

Low reticulocyte count

• Iron deficiency (especially early)
• Anemia of chronic disease (low-normal MCV)
• Chronic renal disease (low erythropoietin)
• Hypothyroidism, adrenal insufficiency, or hypopituitarism
• Primary bone marrow disorder:
  • Aplastic anemia
  • Malignancy, eg, multiple myeloma, leukemia, metastases
  • Myelofibrosis
  • Myelodysplastic syndrome
  • Infection, eg, parvovirus B19 (causes red cell hypoplasia or aplastic anemia)

High reticulocyte count

• Blood loss
• Hemolysis
  • Coombs positive (immune): autoimmune, drugs, infection, lymphoproliferative disease, Rh or ABO incompatibility
  • Coombs negative: intrinsic red cell disease
    1. Abnormal hemoglobin: sickle cell disease, thalassemia, methemoglobinemia
    2. Membrane defect: hereditary spherocytosis, hereditary elliptocytosis, paroxysmal nocturnal hemoglobinuria
    3. Enzyme defect: G6PD deficiency, pyruvate kinase deficiency
  • Coombs negative: extrinsic disease
    1. Microangiopathic hemolytic anemia, eg, thrombotic thrombocytopenic purpura, disseminated intravascular coagulation, prosthetic valve hemolysis
    2. Splenic sequestration
    3. Infection: malaria, Clostridium, Borrelia
    4. Burns