Haemolytic Anaemias Flashcards
Define what anaemia and haemolytic anaemia is.
ANAEMIA = reduced haemoglobin level for the age and gender of the individual
HAEMOLYTIC ANAEMIA = anaemia due to shortened RBC survival
What are some characteristics of the mature RBC?
METABOLIC PATHWAYS:
- glycolytic pathway
- hexose-monophosphate shunt
MEMBRANE:
concave disc
HAEMOGLOBIN:
carries oxygen
If something goes wrong with any of these components, it can lead to haemolytic anaemia.
Describe haemolysis.
It is shortened red cell survival (of around 30 - 80 days).
The bone marrow compensates with increased red blood cell production. This means that we have increased young cells in circulation = reticulocytosis +/- nucleated RBCs.
There are two kinds of haemolysis:
COMPENSATED HAEMOLYSIS: RBC production able to compensate for decreased RBC life span = normal Hb
INCOMPLETELY COMPENSATED HAEMOLYSIS: RBC production unable to keep up with decreased RBC life span = decreased Hb
What are some clinical findings of haemolytic anaemia?
- jaundice
- pallor/fatigue
- splenomegaly
- dark urine
What are some chronic findings of haemolytic anaemia?
- gallstones - pigment
- leg ulcers (NO scavenging)
- folate deficiency
(increased use)
What are some laboratory findings of haemolytic anaemia?
- increased reticulocyte count
- increased unconjugated bilirubin
- increased LDH (lactate dehydrogenase)
- low serum haptoglobin (a protein that binds free haemoglobin)
- increased urobilinogen
- increased urinary haemosiderin
- abnormal blood film
What are some things you would see on the blood film of someone with haemolytic anaemia?
- increased reticulocytes (supravital stain)
- polychromasia
- nucleated RBCs
What are the different classifications of haemolytic anaemia?
INHERITANCE:
- Inherited: hereditary spherocytosis
- Acquired: Paroxysmal nocturnal haemoglobinuria
SITE OF RBC DESTRUCTION:
- Intravascular (inside vessels): Thrombotic thrombocytopenic purpura
- Extravascular (outside of vessels): Autoimmune haemolysis
ORIGIN OF RBC DAMAGE:
- Intrinsic: G6PD deficiency
- Extrinsic: Delayed haemolytic transfusion reaction
Expand on the haemolytic anaemias classified as non-/inherited.
They can be congenital/inherited, such as:
MEMBRANE DISORDERS:
- spherocytosis
- elliptocytosis
ENZYME DISORDERS:
- G6PD deficiency
- pyruvate Kinase deficiency
HAEMOGLOBIN DISORDERS:
- sickle Cell Anaemia
- thalassaemias
They can also be acquired, due to:
- immune factors
- drugs
- mechanical factors
- microangiopathic
- infections
- burns
Examples would be such as Paroxysmal Nocturnal
Haemoglobinuria.
What does a normal red cell membrane consist of?
- lipid bilayer
- integral proteins
- membrane skeleton
If the red cell has defects in its vertical interaction, what would it lead to and what proteins would be likely to be affected?
It could lead to hereditary spherocytosis, and the proteins affected could be:
- Spectrin
- Band 3
- Protein 4.2
- Ankyrin
If the red cell has defects in its horizontal interaction, what would it lead to and what proteins would be likely to be affected?
It could lead to hereditary elliptocytosis, and the proteins affected could be:
- Protien 4.1
- Glycophorin C
- (Spectrin - HPP)
Describe hereditary spherocytosis.
It is a common hereditary haemolytic anaemia. It’s inherited in an autosomal dominant fashion (75%).
It occurs when there are defects in proteins involved in vertical interactions between the membrane skeleton and the lipid bilayer. This causes decreased membrane deformability.
The bone marrow makes a biconcave RBC, but as the membrane is lost, the RBC become spherical.
What are some clinical features of hereditary spherocytosis?
- it’s asymptomatic to severe haemolysis
- causes neonatal jaundice
- jaundice, splenomegaly, pigment gallstones
- reduced eosin-5-maleimide (EMA) binding (it binds to band 3)
- there’s a positive family history
- gives a negative direct antibody test
How would you manage hereditary spherocytosis?
- you would have to monitor blood levels
- give folic acid
- give transfusions
- may have to do a splenectomy