Haemolytic Anaemia

“Anaemia secondary to reduced survival of red blood cells (RBCs)”

• Destruction of RBCs- broadly defined as a reduction in the life span below 100 days (normal 110-120 days)

• Classifications:
  • Inherited vs Acquired
  • Intravascular vs Extravascaular

Risk Factors

• Family history
• Genes for metabolic, haemoglobin, and membrane defects
• Drugs- penicillins, cephalosporins, sulfonamides, sulfasalazine
• Infections – mycoplasma pneumoniae

Aetiology

• Genetic:
  • RBC membrane abnormalities- hereditary spherocytosis
  • Haemoglobin abnormalities- sickle cell, thalassaemia
  • Metabolic defects- G6PD deficiency
• Acquired:
  • Immune- haemolytic disease of newborn, blood transfusion reaction
  • Autoimmune- idiopathic, SLE, chronic lymphatic leukaemia, infections
  • Drugs

Pathophysiology

• Two mechanisms:
  • Intravascular
    • Due to complement fixation, trauma, or other extrinsic factors
    • Prosthetic valves, cardiac valves, G6PD deficiency, disseminated intravascular coagulation
  • Extravascular (most common)
    • RBCs removed from the circulation because they are either intrinsically defective or because of bound immunoglobulins to their surfaces

Clinical Presentation

• Haemolysis:
  • Jaundice
  • Abdominal pain (eg gallstones)
  • Dark urine (haemoglobinuria secondary to intravascular haemolysis)

Investigations

• Haemolytic screen:
  • FBC including reticulocyte count
  • Blood film
  • LDH
  • LFTs (bilirubin)
  • Serum haptoglobin
• Other tests:
  • Direct anti-globulin test
  • Indirect anti-globulin test
  • Haemoglobin electrophoresis
  • Sickle cell screening
• Traditionally causes a NORMOCYTIC ANAEMIA

Management

• Conservative: n/a
• Medical:
  • Administer folic acid
  • Discontinue meds causing haemolysis
  • Transfusion therapyIron therapy
  • Autoimmune haemolytic anaemia therapy:
    • Corticosteroids
    • Azathioprine and cyclophosphamide if steroids fail
    • Rituximab
• Surgical:
  • Splenectomy

Complications

• High-output cardiac failure
• Jaundice
• Iron deficiency