Haemolytic Anaemias Flashcards Preview

Sem 4: TI2 > Haemolytic Anaemias > Flashcards

Flashcards in Haemolytic Anaemias Deck (17):
1

Describe what is meant by haemolytic anaemia and how the body compensates for this condition. 

  • Anaemia caused by shortened RBC survival - i.e. 30-80 days.
  • Normal lifespan is 120 days. 
  • Occurs when incompletely compensated haemolysis - rate of RBC production unable to keep up with reduced RBC lifespan. 
  • Increased haemolysis - reticulocytosis and nucleated RBCs in blood film. 

2

What are the 2 main metabolic pathways used in erythrocytes?

  1. Glycolytic pathway
  2. Hexose-monophosphate shunt

3

Describe the main clinical findings in haemolytic anaemia. 

  • Jaundice
  • Pallor/fatigue
  • Splenomegaly 
  • Dark urine

Haemolytic crises - increased anaemia and jaundice with infections/precipitants.

Aplastic crises - anaemia, reticulocytopenia with parvovirus infection. 

 

 

4

Describe the main findings in chronic haemolysis. 

  • Gallstones - pigment
  • Leg ulcers
  • Folate deficiency - increased use in RBC production

5

What are the main findings on a blood film in haemolytic anaemia?

  • Reticulocytopenia 
  • Nucleated RBCs
  • Immature RBCs in blood increase MCV 
  • Polychromasia in reticulocytes - bluish colour

6

Describe the main inherited conditions that cause haemolytic anaemia. 

Membrane disorders:

  • Hereditary spherocytosis
  • Hereditary elliptocytosis 

Enzyme disorders:

  • G6PD deficiency
  • Pyruvate kinase deficiency

Haemoglobin disorders:

  • Sickle cell anaemia (SCA)
  • Thalassaemias 

7

Name 5 acquired causes of haemolytic anaemia. 

  • Immune 
  • Drugs
  • Microangiopathic
  • Infections - e.g. malaria
  • Paroxysmal nocturnal hemoglobinuria 

8

Describe the cellular membrane defects seen in hereditary spherocytosis and elliptocytosis. 

  • Hereditary spherocytosis - defects in vertical membrane interaction: spectrin, band 3, protein 4.2, ankyrin. 
  • Hereditary elliptocytosis - defects in horizontal membrane interaction: protein 4.1, glycophorin C. 

9

Outline the clinical features and signs/symptoms of hereditary spherocytosis. 

  • 75% cases - autosomal dominant 
  • Defects in vertical interactions between lipid bilayer and membrane skeleton
  • Decreased membrane deformability
  • Bone marrow makes biconcave RBC, but as membrane is lost RBCs become spherical
  • Neonatal jaundice 
  • Jaundice, splenomegaly, pigment gallstones

10

How is hereditary spherocytosis managed?

  • Folic acid supplementation
  • Transfusion 
  • Splenectomy 

11

What are Howell-Jolly bodies and when are they seen in a blood film?

  • Remnants of nucleus - small purple spots seen inside RBCs 
  • Normally removed by the spleen 
  • Seen in splenectomised and hyposplenic patients
  • SCA
  • Coeliac disease 

12

What is hereditary pyropoikilocytosis (HPP)?

  • Membrane disorder similar to severe hereditary elliptocytosis 
  • Severe haemolysis and anaemia
  • Presents with spherocytes and elliptocytes 
  • Associated with defect in spectrin membrane protein

13

Outline the epidemiology, pathophysiology and clinical features of glucose-6-phosphate dehydrogenase (G6PD) deficiency. 

  • Hereditary, X-linked disorder. 
  • Common in African, Asian, Mediterranean and Middle Eastern populations. 
  • Type A in Africans less severe, type B in Mediterraneans more severe. 
  • HMP shunt generates reduced glutathione, protecting the cell from oxidative stress. 
  • G6PD - lack of protection from oxidation. 
  • Oxidation of Hb to form Heinz bodies, oxidised membrane proteins - reduced deformability. 
  • Acute episodes induced by oxidative precipitants.
  • Chronic haemolysis may develop. 

14

Outline the pathophysiology and clinical features of pyruvate kinase deficiency. 

  • Autosomal recessive. 
  • Pyruvate kinase required to generate ATP and essential for membrane cation pumps. 
  • PK deficiency - defect in membrane deformability. 
  • Chronic anaemia - mild to transfusion dependency. 
  • Improves with splenectomy. 

15

Outline the clinical features of beta thalassaemia. 

  • Imbalanced α and β globin chain production.
  • Excess unpaired globin chains are unstable - precipitate and damage RBC and precursors. 
  • Ineffective erythropoiesis and haemolytic anaemia. 
  • β thalassaemia - reduced or absent production of β globin - depending on hetero/homozygous for faulty βallele.
  • β thalassaemia major - 2 β0 alleles.
  • β thalassaemia trait - 1 β0 allele. 

16

Outline the epidemiology, pathophysiology and clinical features of sickle cell disease. 

  • Autosomal recessive. 
  • 1 faulty allele - sickle cell trait. 
  • Sickle cell trait protective against malaria - common in Sub-Saharan Africa, Middle East, India. 
  • 2 faulty alleles - sickle cell disease (SCD). 
  • Point mutation in beta globin gene - glutamic acid > valine at position 6. 
  • Insoluble Hb tetramer - polymerisation and crystallisation > sickle-shaped cells. 
  • Blockage of blood flow in spleen and brain - commonest cause of stroke in childhood. 

17

Describe the 3 main features characteristic of haemolysis. 

  1. Reticulocytosis (and nucleated RBC) 
  2. Unconjugated hyperbilirubinaemia 
  3. Raised lactate dehydrogenase (LDH)