Anemia, general approach


Macrocytic (MCV >100)

  • Megaloblastic anemia: folic acid or Vitamin B12 deficiency
  • Liver disease (target cells)
  • Alcoholism
  • Reticulocytosis
  • Hypothyroidism
  • Myelodysplastic syndrome
  • Antiretrovirals, eg, AZT

Microcytic (MCV < 80)

  • Iron deficiency
  • Thalassemia
  • Anemia of chronic disease
  • Sideroblastic anemia
  • Lead poisoning

Normocytic (MCV 80-100)

  • Low reticulocyte count
  • Iron deficiency (especially early)
  • Anemia of chronic disease
  • 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

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Last updated: December 1, 2014