Sickle cell anaemia


    • 'Sickling' of red blood cells at low pO2 as a result of a defective haemoglobin beta chain (Glu-> Val)

Risk Factors

    • Hypoxia

    • Age

Differential diagnosis

    • Iron deficiency

    • Other causes of anaemia

    • Asthma / other causes of SOB

    • Drug abusers?

    • NB Pain is specific to sickle-cell anaemia

    • Spleen - painful/enlarged (splenomegaly) in sickle-cell


    • Allele is more common in (West) African populations (85 % of cases)

    • Sickel cell trait:

      • Malaria

    • Due to increased RBC turnover with HbS even when heterozygous


    • The deoxygenated form of HbS is insoluble and polymerises

    • HbA is made faster/not degraded as fast c.f. HbS, therefore heterozygotes generally asymptomatic

Clinical features

    • Tiredness, breathlessness, lethargy, especially at low pO2 (after exercise, altitude etc)

    • Malaise, night sweats, sleeplessness

    • Splenomegaly

    • Dactylitis (esp. in infants)

    • Normocytic anaemia

    • Normal reticulocyte count

    • Ventricular hypertrophy ?

    • Developmental (delayed growth, puberty)

    • Occasional 'crises' with severe pain

      • Pain (anywhere)


    • 'Sickled' cells are inflexible and block small capillaries

    • Therefore ischaemia, necrosis

    • Necrotic tissue can be colonised by pathogens e.g. S. aureus

    • Frequent autosplenectomy causing further problems


    • TBC (RBC, MCH, MCHC, Reticulocytes)

      • Low MCH

      • High reticulocyte

    • Bone X-ray

    • Blood film

    • Genetic testing

    • Heel prick test for neonates

    • Hb solubility test

    • Electrophoresis / HPLC for Hb alleles


a) conservative

    • Fluids, warmth, local massage

    • Avoid hypoxia

    • Education

b) medical

    • Prophylactic antibiotics vs. encapsulated bacteria (e.g. Streptococcus pneumoniae, Staphylococcus aureus)

    • Hydroxyurea to stimulate HbF production?

    • Gene therapy

    • Sub-cut. morphine for pain relief

    • Blood transfusion

    • Pre-implantation genetic diagnosis (PGD) for future children ?

c) surgical

    • Excision of ulcers

    • Bone marrow transplant

    • Hip replacement etc. to repair damaged bones / joints


    • Likely to worsen with age

    • Recurrent pain

    • Life-long blood transfusions

    • Mean life expectancy 60 yrs in Western countries

    • Much shorter without medical treatment

      • >50 % die before 1st birthday

      • Especially vulnerable to malaria