Hereditary Spherocytosis

Question 1

What is hereditary spherocytosis and how does it arise?

Answer 1

o Extravascular haemolytic anaemia
o Due to mutations in cytoskeletal proteins involved in maintaining the vertical interactions between the RBC membrane skeleton and the phospholipid bilayer.
o Causes RBCs to become spherical, losing their SA:V ratio and flexibility, meaning they have impaired function and become trapped in the vasculature.
o These spherocytes are recognised by RES macrophages and are removed via extracellular haemolysis.

Question 2

What are the symptoms and their explanations?

Answer 2

o Anaemia, fatigue, pallor, breathlessness – haemolysis of RBCs.
o Splenomegaly – increased RES mediated haemolysis.
o Jaundice – increased bilirubin due to breakdown of RBCs.
o Pigment gallstones – increased haemolysis and bilirubin production.

Question 3

What are the laboratory findings?

Answer 3

o Anaemia – low RBC and low Hb
o Decreased MCV and increased MCHC – spherocytes being small and concentrated
o Increased reticulocyte count
o Increased RDW – red cell distribution width
o Blood film shows spherocytes

Question 4

What further tests should be done?

Answer 4

o Negative DAT
o Biochemistry tests: LDH (increased), bilirubin (increased) and haptoglobin (normal)
o EMA binding test – left shift

Question 5

How is hereditary spherocytosis treated?

Answer 5

o Folic acid
o Laparoscopic splenectomy with antibiotics
o Cholecystectomy for pigment gallstones