Hereditary Spherocytosis

  • Blood film (and HP) contain microspherocytes (due to a loss of membrane, and therefore surface area so that the area of central pallor is lost).
  • HS is a common, usually autosomal dominant, genetic disorder, affecting 1:2000-1:5000 caucasians.
  • HS is highly variable in its clinical manifestations (may be diagnosed at birth (severe), at adulthood or not at all.

Pathogenesis
  • The HS RBC is defective upon its exit from the bone marrow (BM)
  • Defective RBC's have problems with cellular proteins: spectrin and actin.
  • 10X more sodium (Na+) enters the cell than (glucose powers the ATP shunt that removes Na+.
  • As the spleen's environment normally deprives the cell of glucose, Na+ levels increase resulting in an accompanying increase of water (to balance the osmolarity) into the cell - may result in bursting.

    Hereditary Spherocytosis Cell Changes

Haematological Profile:

    Hb Dec (Reflects EVH)
    RCC Dec (Reflects EVH)
    Hct Dec (Reflects EVH)
    WCC N - Inc
    Plt N - Inc
    MCV N - Inc (Microspherocytes have normal volume)
    MCH N - Inc
    Haemoglobinisation Normochromic
    Anisocytosis ++ (Polychromatic Macrocytes)
    Poikilocytosis ++ - +++ (Microspherocytes)
    Immature Forms Polychromasia + - +++ (Nucleated RBCs if severe)

Complications:

    • Patients present with classic symptoms of HA:
      • Anaemia
      • Jaundice
      • Splenomegaly
      • Gall Stones
      • Ulcers
    • Aplastic anaemia due to concurrent infection with parvovirus B19
    • Megaloblastic anaemia - folate deficiency due to the constant RBC regeneration.

Treatment:

    • Splenectomy, if more than 5 years old (corrects anaemia due to haemolysis, still more susceptible to infection (vaccination becomes even more essential) but live a normal life)
    • Differentiate from Autoimmune Haemolytic Anaemia (AIHA) which has a similar blood picture.
      • Direct anti-huIg test
      • Test for antibody or complement on RBC of patient
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