Hereditary Spherocytosis
A 9-year-old boy has had recurrent scleral icterus and exercise intolerance since the age of 2 years. Haemoglobin is 9.4 g/dL, reticulocytes 9%, unconjugated bilirubin 78 µmol/L, and the direct antiglobulin test is negative. The spleen is palpable 4 cm below the costal margin, and ultrasound shows multiple pigment gallstones. His father and paternal grandfather had lifelong anaemia. Splenectomy is expected to abolish haemolysis in which of the following disorders?
- A.Hereditary spherocytosisCorrect
- B.Sickle cell anaemia
- C.Beta thalassaemia major
- D.Glucose-6-phosphate dehydrogenase deficiency
Explanation
Hereditary spherocytosis results from defects in the red cell membrane skeleton proteins spectrin, ankyrin, band 3 or protein 4.2, which cause loss of membrane surface area and conversion of biconcave discs into rigid spherocytes. These spherocytes are structurally abnormal but survive normally in the circulation; they are destroyed almost exclusively by the reticuloendothelial cords of the spleen. Removing the spleen therefore removes the site of destruction and normalises red cell survival, haemoglobin, reticulocyte count and bilirubin, even though the underlying membrane defect and the spherocytes themselves persist. This is why splenectomy is described as effectively curative of the haemolysis in this condition, and why it is offered for severe disease, growth failure or recurrent pigment gallstones, usually after the age of 6 years and after pneumococcal, meningococcal and Haemophilus influenzae type b immunisation. In sickle cell anaemia the primary problem is intravascular polymerisation of haemoglobin S, and most children autosplenectomise spontaneously, so splenectomy does not stop the haemolysis or the vaso-occlusive crises. In beta thalassaemia major splenectomy may reduce transfusion requirement when hypersplenism develops, but ineffective erythropoiesis in the marrow continues and lifelong transfusion is still needed. In glucose-6-phosphate dehydrogenase deficiency the haemolysis is oxidative and largely intravascular and episodic, so splenectomy provides no benefit and management is avoidance of oxidant triggers.
Why each option
- A.
- Correct. Spherocytes are destroyed by the spleen, so splenectomy eliminates the haemolysis and normalises haemoglobin and bilirubin despite the persisting membrane defect.
- B.
- Sickling and vaso-occlusion are intrinsic to the red cell and to the microcirculation; children usually autosplenectomise, and removing the spleen does not stop haemolysis.
- C.
- Splenectomy may lower transfusion requirements in hypersplenism, but ineffective erythropoiesis continues and transfusion dependence persists.
- D.
- Haemolysis is oxidant-triggered and largely intravascular and episodic; management is avoidance of fava beans and oxidant drugs, not splenectomy.
Reference: Nelson Textbook of Pediatrics, 22nd ed., 2024, Hereditary Spherocytosis
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