Haemotology Flashcards
What are the different microcytic anaemias?
- Iron deficiency
- Haemoglobinopathies e.g. Thalassaemia, sickle cell
- Anaemia of chronic disease e.g. CKD and so lack of EPO
WHAT IS THALASSAEMIA?
https://www.youtube.com/watch?v=uK_uIBHnOWo&t=4s
The thalassaemias are genetic diseases of unbalanced Hb synthesis, with under-production (or no production) of one globin chain
What is the pathology of thalassaemia?
What happens to the red blood cells?
- Unmatched globins precipitate
- Damaging RBC membranes
- Causing their haemolysis while still in the marrow.
What are the different types of Thalassaemia?
What different treatments do they require?
Thalassaemia Major
Transfusion dependent
Thalassaemia Intermedia
Less severe anaemia and can survive without regular blood transfusions
Thalassaemia Carrier/heterozygote
Asymptomatic.
What type of anaemia is thalassaemia?
Microcytic
WHAT IS BETA THALASSAEMIA?
What do you get less of?
What happens as a result?
In homozygous beta-thalassaemia, little/no normal beta chain production
EXCESS alpha chains.
Alpha chains combine w. whatever beta, delta or gamma chains available increased production of HbA2& HbF.
What is the cause of beta thalassemia?
Which chromosome is it defected in?
Point mutations in beta-globin genes
Chromosome 11
Decreased beta-chain production (beta+) or absence (beta0)
What is beta thalassemia major called?
Beta thalassaemia major (Cooley’s anaemia) denotes abnormalities in both beta-globin genes.
When does beta thalassaemia major present?
6 -12 months
What are the symptoms of beta thalassaemia major?
Failure to feed, listless, crying, pale.
Bones widen due to increased activity
Skull bossing
Anaemia
Hepatosplenomegaly
Lots of RBCs need to be destroyed
What is beta thalassaemia minor or trait?
This is a carrier state
What are the symptoms of beta thalassaemia minor?
Usually asymptomatic
Mild, well-tolerated anaemia (Hb >90g/L)
What are the symptoms of beta thalassaemia intermedia?
- Moderate anaemia but not requiring transfusions
- There may be splenomegaly
What are the tests for Beta thalassaemia?
-
FBC & film
- Hypochromic & microcytic anaemia
- Target cells are seen
- Reduced reticulocytes and nucleated RBCs
-
Dx by Hb electrophoresis
- Shows increased HbF & absent/low HbA.
What is the treatment for beta thalassaemia major?
BLOOD TRANSFUSIONS
Give iron chelation
Desferrioxamine
Decrease iron loading
Ascorbic acid
Increased urinary excretion of iron.
Long term folic acid supplements.
What happens when a child with Thalassaemia major has treatment by continuous blood transfusions?
Children require lifelong blood transfusions.
Consequence is an progressive increase in body iron load.
Can’t eliminate the excessive iron
Patients inexorably develop a clinically worsening hemosiderosis
Liver and spleen, leading to liver fibrosis and cirrhosis.
Endocrine glands and the heart, resulting in diabetes, heart failure and premature death.
Death ultimately occurs, mainly due to cardiac hemosiderosis.
What does degree of symptoms depends of in alpha Thalassaemia?
4 deletions
HbBarts, infants are STILLBORN(hydrops fetalis).
3 deletions
SEVERE anaemia.
2 deletions
Often ASYMP. carrier, may have mild anaemia.
1 deletion
Close to normal.
WHAT IS SICKLE CELL ANAEMIA (GENETICS)?
What type of anaemia is it?
https://www.youtube.com/watch?v=1ql-X60CUNQ&t=6s
- Sickle-cell anaemia is an autosomal recessive disorder causing production of abnormal beta globin chains.
- Microcytic anaemia
What is haemoglobin S?
Variant haemoglobin arising because of a point mutation in the b globin gene.
What happens with a carrier of sickle cell disease?
Carriers of HbS are symptom free
Carriage offers protection against falciparum malaria
Sickle cell diseases arise in the homozygous state (SS) or in combined heterozygotes (SC or Sb thalassaemia).
What gene changes occur in sickle cell anaemia?
- Thiamine for adenine in 6th codon
- Beta globin gene
- Glutamic acid leaves
- Valine comes in