Hemoglobin

Thalassemia

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Thalassemia

  • Background
  1. Thalassemia is derived from Greek word "thalassa" for sea
  • Epidemiology
  1. Thalassemia accounts for one third of all globin abnormalities
  2. Gender: Males and females affected equally
  3. Prevalence of Thalassemia
    1. World wide: 1.7% (4.4 per 10,000 live births)
    2. Among at risk ethnicities: 5-30%
  4. Ethnicity
    1. Alpha Thalassemia
      1. African descent (2% Incidence)
      2. Asian patients (Incidence common)
    2. Beta Thalassemia
      1. Southern Italy and Mediterranean islands (0.1% Incidence)
      2. Central Africa
      3. Southeast Asia
  • Pathophysiology
  1. Cluster of Autosomal Recessive hematologic disorders affecting Hemoglobin
  2. Globin chain abnormalities result in unbalanced red cells that are susceptible to Hemolysis
  • Labs
  1. Complete Blood Count
    1. Hemoglobin or Hematocrit consistent with Anemia
    2. Mean Corpuscular Volume (MCV)
      1. Hematocrit >30% and MCV low but >80 fl: Iron Deficiency Anemia more likely
      2. Hematocrit >30% and MCV <75 fl: Thalassemia more likely
        1. Cut-off varies by age (<70 fl up to 6 years, <75 fl in age 7-12, <80 fl in adults)
    3. Red Cell Distribution Width (RDW)
      1. Microcytosis with Normal RDW: Thalassemia is most likely
      2. Microcytosis with Increased RDW: Sideroblastic Anemia, Iron Deficiency Anemia, Thalassemia
    4. Mean Corpuscular Volume to Red Blood Cell Count ratio (applies to evaluation in children)
      1. See Mentzer Index
      2. Ratio <13: Thalassemia
      3. Ratio >13: Iron Deficiency Anemia, Hemoglobinopathy
  2. Normal Iron study indices (no Iron Deficiency Anemia)
    1. Ferritin normal (often >100 ng/ml)
    2. Other iron studies typically not needed unless inflammation is present
      1. Total Iron Binding Capacity normal
      2. Serum Iron normal
  3. Variable Reticulocyte Index
    1. May see Reticulocytosis or Reticulocytopenia
  4. Peripheral Smear
    1. Hemolytic Anemia signs
    2. Red Blood Cell Inclusion bodies
  • Diagnosis
  1. Hemoglobin Electrophoresis