Haemolytic anaemia Flashcards
What are the 2 classes of haemolytic anaemia?
Acquired: AI, MAHA, Infection, Drugs
Congenital: Membrane defect, Metabolic defect, haemoglobinopathies
What metabolic defect can cause haemolytic anaemia?
G6PD deficiency
Intravascular haemolysis
X-linked recessive (ONLY M)
Oxidative stressors precipitate haemolysis
How can G6PD deficiency be detected?
Haemoglobinuria for days after oxidative stress
Blood film: Heinz bodies, Bite cells
What membrane defect can cause haemolytic anaemia?
Hereditary spherocytosis: normal MCV, loss of central pallor
Extravascular haemolysis
Autosomal dominant
How can hereditary spherocytosis be detected?
Osmotic fragility test: give hypotonic solution- RBC lysis
Coombs Test negative
Why does Parvovirus B19 have life threatening implications in hereditary spherocytosis?
Can cause aplastic crisis:
Infects BM, preventing production of RBCs so have to rely on those already circulating
In HS lifespan of RBC is only 30 days- will quickly be deficient
What type of haemolysis occurs in AI haemolytic anaemia? How is this detected?
Intravascular haemolysis
Coombs’ test
Warm agglutinins: IgG antibodies
Cold agglutinins: IgM antibodies
What infection can cause haemolytic anaemia?
Malaria
What drugs can cause haemolytic anaemia?
Dapsone (anti-leprosy abx)
Penicillin
What occurs in microangiopathic haemolytic anaemia?
Shearing of RBCs as they pass through in small vessels obstructed by platelet aggregates + micro thrombi
Intravascular haemolysis
What is seen on blood film in MAHA?
Schistocytes
Give 3 types of MAHA
Haemolytic Uraemic Syndrome
Disseminated intravascular Coagulation
Thrombotic Thrombocytopenic Purpura
What may be seen on blood tests in haemolytic anaemias?
Hb low Haptoglobin low (if intravascular, as binds to free Hb) High Unconjugated BR High LDH High reticulocytes (high MCV)
What is haemolytic anaemia?
premature erythrocyte breakdown causing shortened erythrocyte life span (< 120 days) with anaemia
Describe the epidemiology of haemolytic anaemia
COMMON
Genetic causes prevalent in African, Mediterranean + Middle Eastern
Hereditary spherocytosis is the most common inherited haemolytic anaemia in northern Europe
List 4 general signs of haemolytic anaemia
Pallor
Jaundice
Hepatosplenomegaly
Haematuria
What investigations other than bloods would you perform for haemolytic anaemia?
U+Es: raised in TTP/ HUS
Folate: deficiency results in macrocytes
Blood Film: to identify abnormal cells
Urine
Direct Coombs’ Test: Tests for AIHA, identifies erythrocytes coated with antibodies
Osmotic fragility test: identifies membrane abnormalities
Hb Electrophoresis or Enzyme Assays: exclude ddx
Bone Marrow Biopsy (rarely performed)
What may be seen on a blood film in haemolytic anaemia?
Leucoerythroblastic picture Macrocytosis Nucleated erythrocytes or reticulocytes Polychromasia May identify specific abnormal cells such as: Spherocytes Elliptocytes Sickle cells Schistocytes Bite cells Malarial parasites
What may be seen in the urine in haemolytic anaemia?
High urobilinogen (increased haem catabolism) Haemoglobinuria (intravascular haemolysis) Haemosiderinuria (increased haem catabolism)