Hematology and Oncology Book

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Microcytic Anemia

Aka: Microcytic Anemia
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  1. See Also
    1. Anemia
    2. Anemia Clinical Clues
    3. Anemia Evaluation
  2. Causes
    1. Iron Deficiency Anemia (most common)
      1. Decreased Serum Iron level
      2. Increased Total Iron Binding Capacity
      3. Decreased Transferrin Saturation
    2. Thalassemia
      1. Normal iron studies
      2. Differentiated with Hemoglobin electrophoresis
    3. Anemia of Chronic Disease
      1. Decreased Serum Iron, TIBC and Transferrin Saturation
    4. Sideroblastic Anemia
      1. Similar workup as with Thalassemia
    5. Lead Poisoning
  3. Labs
    1. Complete Blood Count
      1. See Hemoglobin Cutoffs for Anemia
      2. See Hematocrit Cutoffs for Anemia
      3. Mean Corpuscular Volume (MCV) <80
        1. See MCV Cutoffs for Microcytic Anemia
        2. MCV cutoff varies by age and per reference
    2. Serum Iron
      1. Decreased in Iron Deficiency Anemia and Anemia of Chronic Disease
    3. Total Iron Binding Capacity (TIBC)
      1. Increased in Iron Deficiency Anemia
      2. Decreased in Anemia of Chronic Disease
    4. Transferrin Saturation
      1. Near complete saturation in Sideroblastic Anemia
      2. Less than 5% saturated in Iron Deficiency Anemia
    5. Ferritin Level
      1. Ferritin <15 ng/ml suggests Iron Deficiency Anemia
      2. Ferritin is acute phase reactant and also elevated in chronic inflammation
        1. Use cutoff of <50 ng/ml to diagnose Iron Deficiency Anemia when comorbid inflammatory condition present
    6. Reticulocyte Index <1% (Reticulocytopenia)
      1. See Anemia for causes of Reticulocytosis
    7. Mean Corpuscular Volume to Red Blood Cell Count ratio
      1. See Mentzer Index
      2. Ratio <13: Thalassemia
      3. Ratio >13: Iron Deficiency Anemia, Hemoglobinopathy
  4. Labs: Hemoglobin Electrophoresis
    1. Indications
      1. Suspected Hemoglobinopathy (e.g. Thalassemia)
      2. Normal Serum Iron, Transferrin Saturation, and TIBC (esp. in young patients)
    2. Interpretation
      1. Increased Hemoglobin A2 Level
        1. Beta Thalassemia
      2. Normal Hemoglobin A2 Level
        1. Sideroblastic Anemia
        2. Alpha-Thalassemia trait
  5. References
    1. Shine (1997) Am Fam Physician 55(7):2455-62

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