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Updated: Mar 5 2021

Hereditary Spherocytosis

Images for anemia - moises d.jpg
  • Snapshot
    • A 25-year-old pregnant woman presents to her obstetrician reporting yellow eyes, yellow skin, and dark urine. She reports having a family history of “jaundice,” and some of her relatives have undergone splenectomy. She states she has had periodic jaundice throughout her life, but now that she is pregnant, she is constantly jaundiced. A peripheral smear shows spherocytes.
  • Introduction
    • Overview
      • hereditary spherocytosis is a hereditary disorder characterized by small, round red blood cells (RBCs) without central pallor, resulting in premature removal by the spleen and hemolytic anemia
        • treatment is usually splenectomy
    • Epidemiology
      • incidence
        • most common cause of hereditary hemolytic anemia in patients of northern European descent
    • Pathogenesis
      • mechanism
        • intrinsic defect in RBC membrane proteins leading to decreased RBC membrane surface area and increased fragility
        • abnormal RBCs are lysed by the spleen, resulting in extravascular hemolysis
    • Genetics
      • inheritance pattern
        • autosomal dominant
      • mutations
        • multiple mutations implicated, leading to variety of clinical manifestations, ranging from asymptomatic to fulminant hemolytic anemia
        • most commonly caused by spectrin deficiency
        • less commonly caused by ankyrin mutation
  • Presentation
    • History
      • may have family history of relatives who have undergone splenectomy
      • may have a history of intermittent scleral icterus, jaundice, and dark urine color, often associated with viral infections
    • Symptoms
      • clinical severity varies
        • onset may occur in neonatal period, or in adulthood in the context of environmental stress
        • cholelithiasis may be the presenting sign
          • gallstones are pigmented
      • common symptoms
        • colicky abdominal pain
    • Physical exam
      • inspection
        • splenomegaly
        • jaundice
          • may be triggered by stress, fatigue, pregnancy, or infection
        • pallor
        • dark urine
  • Studies
    • Osmotic fragility test
      • increased fragility
    • Serum labs
      • normocytic anemia
      • ↑ reticulocyte count
      • ↑ bilirubin
      • ↑ mean corpuscular hemoglobin concentration (MCHC)
    • Peripheral blood smear
      • round RBCs (spherocytes) without central pallor
  • Differential
    • Autoimmune hemolysis
      • key distinguishing factor
        • may also present with spherocytes but is Coombs positive
    • Gilbert syndrome
      • key distinguishing factors
        • may also present with jaundice intermittently, but patients often also have abdominal cramps, fatigue, and malaise
        • laboratory studies show normal reticulocyte count and peripheral blood smear
  • Treatment
    • Medical
      • folic acid supplementation
        • indications
          • folic acid is required for continued erythropoiesis
          • folic acid deficiency can result in megaloblastic crisis
      • RBC transfusion
        • indication
          • aplastic crisis
    • Surgical
      • splenectomy
        • indications
          • definitive treatment
          • can be deferred in patients with mild HS (hemoglobin > 11 g/dL)
          • patients must undergo vaccination against pneumococcus and H influenzae prior to splenectomy
  • Complications
    • Parvovirus B19-induced aplastic crisis
    • Cholecystitis
    • Megaloblastic crisis
      • secondary to folate deficiency
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