Haemolytic Anaemia Flashcards
Definition
Premature erythrocyte breakdown causing shortened erythrocyte life span (< 120 days) with anaemia
Aetiology (hereditary)
o Membrane Defects
• Hereditary spherocytosis
• Elliptocytosis
o Metabolic Defects
• G6PD deficiency
• Pyruvate kinase deficiency
o Haemoglobinopathies
• Sickle cell disease
• Thalassemia
Aetiology (acquired)
o Autoimmune
• Antibodies attach to erythrocytes causing intravascular and extravascular
haemolysis
o Isoimmune
• Transfusion reaction
• Haemolytic disease of the newborn
o Drugs
• Penicillin
• Quinine
• NOTE: this is caused by the formation of a drug-antibody-erythrocyte complex
o Trauma
• Microangiopathic haemolytic anaemia (caused by RBC fragmentation in abnormal microcirculation)
▪ E.g. haemolytic uraemic syndrome, DIC, malignant hypertension
o Infection
• Malaria
• Sepsis
o Paroxysmal nocturnal haemoglobinuria
Epidemiology
- COMMON
- Genetic causes are prevalent if African, Mediterranean and Middle Eastern populations
- Hereditary spherocytosis is the most common inherited haemolytic anaemia in northern Europe
Presenting symptoms
- Jaundice
- Haematuria
- Anaemia
Signs on physical examination
- Pallor
- Jaundice
- Hepatosplenomegaly
Investigations (bloods)
o FBC: • Low Hb • High reticulocytes • High MCV • High unconjugated bilirubin • Low haptoglobin (a protein that binds to free Hb released by red blood cells)
o U&Es
o Folate
Investigations (blood film)
o Leucoerythroblastic picture
o Macrocytosis
o Nucleated erythrocytes or reticulocytes
o Polychromasia
o May identify specific abnormal cells such as: • Spherocytes • Elliptocytes • Sickle cells • Schistocytes • Malarial parasites
Investigations (urine)
o High urobilinogen
o Haemoglobinuria
o Haemosiderinuria
Investigations (other)
• Direct antiglobulin test/Coombs’ Test
o Tests for autoimmune haemolytic anaemia
o Identifies erythrocytes coated with antibodies
• Osmotic fragility test or Spectrin mutation analysis
o Identifies membrane abnormalities
• Ham’s Test
o Lysis of erythrocytes in acidified serum in paroxysmal nocturnal haemoglobinuria
• Hb Electrophoresis or Enzyme Assays
o To exclude other causes
• Bone Marrow Biopsy (rarely performed)