Haemolytic anaemia

• Haemolytic anaemia involves the destruction of red blood cells resulting in a low haemoglobin concentration, it can be inherited or acquired
• Inherited causes of haemolytic anaemia:

  • Hereditary spherocytosis
  • Thalassaemia
  • Sickle cell anaemia
  • G6PD deficiency
• Acquired causes:

  • Autoimmune haemolytic anaemia
  • Alloimmune - transfusion reactions and haemolytic disease of the newborn
  • Microangiopathic haemolytic anaemia
  • Prosthetic valve-related haemolysis
• Haemolysis can occur in 2 locations:

  • Extravascular haemolysis occurs primarily in the spleen - more common
  • Intravascular haemolysis within the circulation
• Typical symptoms:

  • Fatigue
  • Dizziness, pre-syncope, or syncope
  • SOB
  • Reduced exercise tolerance
  • Palpitations
  • If intravascular - back pain and dark urine
• Non-specific signs of anaemia on exam:

  • Pallor
  • Tachycardia and flow murmurs - hyperdynamic circulation
  • High-output heart failure - cardiac output is high but insufficient to meet metabolic demands of the body
• More specific signs of haemolysis:

  • Pre-hepatic jaundice - unconjugated hyperbilirubinemia
  • Splenomegaly
  • Dark urine
  • Gall stones - RUQ pain
• Urinalysis - increased urinary urobilinogen

  Conjugated bilirubin will be negative
• Lab investigations:

  • FBC - normocytic anaemia
  • Raised reticulocyte count - reticulocytosis
  • Raised unconjugated (indirect) bilirubin
  • Raised LDH
  • Decreased plasma haptoglobin - bound to large amounts of free haemoglobin in the circulation
  • Direct coombs test - autoimmune
• Peripheral blood smear:

  • Hypochromic, microcytic - indicated thalassaemia
  • Sickled red blood cells - sickle cell anaemia
  • Schistocytes - fragments of red blood cells that occur due to abnormal shearing forces - microangiopathic haemolytic anaemias
  • Spherocytes - hereditary spherocytosis or autoimmune haemolysis
  • Malignant cells
  • Heinz bodies - G6PD deficiency
• Hereditary spherocytosis:

  • Most common inherited haemolytic anaemia
  • Autosomal dominant
  • Fragile, sphere-shaped red blood cells that easily break down when passing through the spleen
  • Presentation - anaemia, jaundice, gallstones and splenomegaly
  • Aplastic crisis in the presence of parvovirus
  • Spherocytes on blood film
  • Treatment - folate supplements, blood transfusions and splenectomy
• G6PD deficiency:

  • Defect in an enzyme that protects cells from oxidative damage
  • Acute episodes of haemolytic anaemia triggered by infections, drugs or fava beans
  • Presentation - jaundice (often neonatal), gallstones, anaemia, splenomegaly
  • Heinz bodies on blood film
  • Diagnosis via G6PD assay
• Autoimmune haemolytic anaemia:

  • Antibodies created against the patient's red blood cells
  • Warm or cold based on the temperature at which the auto-antibodies destroy red blood cells
  • Warm autoimmune haemolytic anaemia is more common - usually idiopathic
  • Management: blood transfusions, prednisolone, rituximab and splenectomy
• Microangiopathic haemolytic anaemia:

  • Destruction of red blood cells as they travel through the circulation
  • Abnormal activation of the clotting system, thrombi partially obstructing the small blood vessels
  • Obstructions churn the red blood cells, causing haemolysis
  • Haemolytic uraemic syndrome
  • DIC
  • Thrombotic thrombocytopenic purpura (TTP)
  • Cancer
  • Schistocytes on blood film
• Prosthetic valve haemolysis:

  • Occurs in both bio prosthetic and metallic valve replacement
  • Turbulent flow around the valve and the shearing of the red blood cells
  • Oral iron and folic acid supplementation
  • Blood transfusions
  • Revision surgery may be required