Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 13-10: Hereditary Spherocytosis + Key Features Download Section PDF Listen +++ ++ 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 Download Section PDF Listen +++ ++ 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 Chronic hemolysis causes Jaundice Pigment (calcium bilirubinate) gallstones, leading to attacks of cholecystitis Medial malleolar skin ulcers Palpable spleen + Diagnosis Download Section PDF Listen +++ ++ 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 maleimide) binding by flow cytometry is another diagnostic tool + Treatment Download Section PDF Listen +++ ++ Folic acid, 1 mg orally once daily Splenectomy Eliminates site of hemolysis May not be necessary in mild cases discovered late in adult life