I. Definition and pathophysiology

  1. Most common heritable cause of hemolytic anemia among people of Northern European descent
  2. Usually autosomal dominant inheritance
  3. Caused by defects in the RBC membrane-to-cytoskeleton attachments, resulting in a spheroid rather than discoid shape to the RBC
  4. RBCs are thus more susceptible to consumption within the spleen, causing hemolytic anemia

II. Clinical features and diagnosis

  1. Can have severe anemia requiring transfusion, no anemia, or anything in between
    1. In severe cases, anemia can develop in neonatal period but rarely before 3wks of life
  2. Usually have jaundice in proportion to severity of anemia
  3. Can have mild splenomegaly (or none)
  4. Can develop "pigmented" gallstones
  5. Common lab findings:
    1. Increased mean corpuscular hemoglobin concentration (36 or more)
    2. High reticulocyte count (though usually < 10%)
    3. Reticulocytosis on peripheral smear (nonspecific to hereditary spherocytosis-other hemolytic anemias as well as hemoglobinopathies, hepatic disease, G6PD deficiency, and other conditions can be associated with this finding)
    4. Sometimes, elevated serum bilirubin (though usually negative urine bilirubin)
    5. Negative direct Coombs' test
  6. Specific diagnosis
    1. Not e hat above findings (including spherocytosis on peripheral smear) are nonspecific
    2. eosin-5-maleimide (EMA) binding dye test (sensitivity 96%; specificity of 99% for hereditary spherocytosis)
    3. Osmotic fragility testing (less sensitive/specific than EMA)

III. Treatment

  1. Mild cases may not require treatment
  2. Moderate-to-severe cases
    1. Folic acid 2-5 mg/day may help prevent aplastic crises
    2. Blood transfusions if severe anemia is present
    3. Splenectomy in severe cases

(Sources include Core Content Review of Family Medicine, 2012)