Red Blood Cell Case Studies


CASE 4: Hereditary spherocytosis


Clinical History:

A 30-year-old woman has the onset of fever, abdominal pain, nausea over the past day. On physical examination her vital signs include temperature 38 C, pulse 102/minute, respirations 20/minute, and blood pressure 95/50 mm Hg. She has scleral icterus. Her spleen tip is palpable, but there is no lymphadenopathy or hepatomegaly. She has Hgb 11.1 g/dL, Hct 28.8%, MCV 77 fL, platelet count 273,400/microliter, and WBC count 8900/microliter. The direct and indirect Coombs tests are negative. A month ago, a CBC had the findings shown.
  1. Describe her peripheral blood findings.

    2. The RBC morphology shows small cells that lack central pallor (spherocytes). She has reticulocytosis and polychromasia.

  2. What is the diagnosis from these findings?

    3. Hereditary spherocytosis.

  3. Which of the following is the most likely genetic inheritance pattern for her condition?

    4. A. Autosomal dominant, European ancestry
    B. X-linked, Asian ancestry
    C. Autosomal recessive, Middle Eastern ancestry
    D. Autosomal recessive, West African ancestry
    E. Sporadic occurrence

    Answer: A

  4. Which of the following is most likely to initiate an aplastic crisis in this patient?

    5. A. Quinacrine
    B. Parvovirus infection
    C. Decreased oxygen tension
    D. Exposure to cold
    E. Transfusion

    Answer: B Parvovirus (sometimes called 'fifth disease') infects RBC precursors and can lead to a temporary shutdown in RBC production. In a person whose marrow is already working at increased production (such as persons with RBC membrane disorders and persons with hemoglobinopathies such as sickle cell anemia), the effect of parvovirus infection is more dramatic than in persons with normal erythropoiesis.

  5. How do you explain the appearance of her RBCs?

    6. Hereditary spherocytosis results from mutations in spectrin and/or ankyrin gene. Spectrin is a cytokeletal membrane protein that aids in maintaining the RBC shape. This destabilizes the RBC membrane and makes the RBC less deformable and less able to pass through the splenic sinusoids, making it more likely to be trapped or damaged. Thus, there is mild hemolysis. The marrow responds by increasing RBC production and releasing more reticulocytes.