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Key Features

  • Disorder of RBC membrane, leading to chronic hemolytic anemia

  • Autosomal dominant disease of variable severity

  • Membrane defect is in spectrin or actin, RBC skeleton proteins, resulting in decreased surface–volume ratio and a spherical RBC shape, which is less deformable

  • Hemolysis occurs because of trapping of RBCs within the spleen and their premature removal by splenic macrophages

Clinical Findings

  • Often diagnosed in childhood, but milder cases discovered incidentally late in life. Family history often positive

  • Anemia may or may not be present because bone marrow may be able to compensate for shortened RBC survival

  • Severe anemia (aplastic crisis) may occur with folic acid deficiency or infection

  • Jaundice and pigment (calcium bilirubinate) gallstones and cholecystitis in chronic hemolysis

  • Palpable spleen


  • Hyperchromic red blood cells (elevated mean corpuscular hemoglobin concentration [MCHC])

  • Anemia of variable severity; hematocrit may be normal

  • Increased MCHC, often > 36 g/dL

  • Reticulocytosis present

  • Peripheral blood smear shows small percentage of spherocytes, small cells that have lost their central pallor

  • Indirect bilirubin often increased

  • Coombs test negative

  • Increased osmotic fragility (abnormally vulnerable to swelling induced by hypotonic media) can be demonstrated by ektacytometry

  • EMA (eosin-5 meleimide) binding by flow cytometry is another diagnostic tool


  • Folic acid, 1 mg orally once daily

  • Splenectomy, which eliminates site of hemolysis

  • Splenectomy may not be necessary in mild cases discovered late in adult life

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