Overview
Sickle cell anaemia is an inherited disorder affecting haemoglobin synthesis, resulting in 'sickling' of red blood cells and resultant complications.
Sickle cell disease is a more broad term that includes sickle cell anaemia, sickle beta thalassaemia and haemoglobin SC disease.
Pathogenesis
Sickle cell disease is inherited in an autosomal recessive fashion, and occurs due to a mutation in beta globin chain gene (genotype βSβS), resulting in haemoglobin S synthesis.
Haemoglobin S tends to polymerise in low oxygen settings, resulting in sickling of red blood cells; these deformed cells have a shortened lifespan and cause occlusions within blood vessels as well as endothelial dysfunction.
Manifestations
Complications of Sickle Cell Anaemia
- Haemolytic anaemia
- Hypersplenism (early) - anaemia, thrombocytopaenia
- Hyposplenism (late) - increased risk of infection, thrombocytosis
- Vaso-occlusive disease - acute pain crises, stroke, acute chest syndrome, avascular necrosis, pulmonary hypertension, renal infarction, other micro-infarcts
- Aplastic crisis (acute anaemia)
Diagnosis
Test Findings in Sickle Cell Anaemia
Full Blood Count & Film
- Normocytic normochromic anaemia
- Anisocytosis: variation in red cell size
- Poikilocytosis - sickle cells, elliptocytes
- Basophilic stippling
- Immature red cells - polychromasia / nucleated red blood cells
- Evidence of hyposplenism - target cells, Howell Jolly bodies, Pappenheimer bodies
Other Tests
- Sickle solubility testing -
- High performance liquid chromatography / haemoglobin electrophoresis - presence of haemoglobin S with a lack of haemoglobin A
Next Page
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------