Haemolytic Anaemias Flashcards Preview

Sem 4: TI2 > Haemolytic Anaemias > Flashcards

Flashcards in Haemolytic Anaemias Deck (17)
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1
Q

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

A
  • 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
Q

What are the 2 main metabolic pathways used in erythrocytes?

A
  1. Glycolytic pathway
  2. Hexose-monophosphate shunt
3
Q

Describe the main clinical findings in haemolytic anaemia.

A
  • Jaundice
  • Pallor/fatigue
  • Splenomegaly
  • Dark urine

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

Aplastic crises - anaemia, reticulocytopenia with parvovirus infection.

4
Q

Describe the main findings in chronic haemolysis.

A
  • Gallstones - pigment
  • Leg ulcers
  • Folate deficiency - increased use in RBC production
5
Q

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

A
  • Reticulocytopenia
  • Nucleated RBCs
  • Immature RBCs in blood increase MCV
  • Polychromasia in reticulocytes - bluish colour
6
Q

Describe the main inherited conditions that cause haemolytic anaemia.

A

Membrane disorders:

  • Hereditary spherocytosis
  • Hereditary elliptocytosis

Enzyme disorders:

  • G6PD deficiency
  • Pyruvate kinase deficiency

Haemoglobin disorders:

  • Sickle cell anaemia (SCA)
  • Thalassaemias
7
Q

Name 5 acquired causes of haemolytic anaemia.

A
  • Immune
  • Drugs
  • Microangiopathic
  • Infections - e.g. malaria
  • Paroxysmal nocturnal hemoglobinuria
8
Q

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

A
  • 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
Q

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

A
  • 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
Q

How is hereditary spherocytosis managed?

A
  • Folic acid supplementation
  • Transfusion
  • Splenectomy
11
Q

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

A
  • Remnants of nucleus - small purple spots seen inside RBCs
  • Normally removed by the spleen
  • Seen in splenectomised and hyposplenic patients
  • SCA
  • Coeliac disease
12
Q

What is hereditary pyropoikilocytosis (HPP)?

A
  • Membrane disorder similar to severe hereditary elliptocytosis
  • Severe haemolysis and anaemia
  • Presents with spherocytes and elliptocytes
  • Associated with defect in spectrin membrane protein
13
Q

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

A
  • 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
Q

Outline the pathophysiology and clinical features of pyruvate kinase deficiency.

A
  • 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
Q

Outline the clinical features of beta thalassaemia.

A
  • 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 β0 allele.
  • β thalassaemia major - 2 β0 alleles.
  • β thalassaemia trait - 1 β0 allele.
16
Q

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

A
  • 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
Q

Describe the 3 main features characteristic of haemolysis.

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