Haem: Thalassaemia & G6PD Flashcards
(38 cards)
What is thalassaemia?
Refers to a genetic defect in the protein chains that make up Hb.
Defects in the alpha globin chains –> alpha thalassaemia.
Defects in beta globin chains –> beta thalassaemia
Inheritance of thalassaemia?
Autosomal recessive
What is the overall effect of thalassaemia?
Varying degrees of anaemia, depending on the type and mutation.
What causes splenomegaly in thalassaemia?
In patients with thalassaemia, the RBCs are more fragile and breakdown more easily.
In patients with thalassaemia, the spleen collects all the destroyed RBCs, resulting in splenomegaly (as the spleen normally acts as a sieve to filter the blood and remove older blood cells).
How is the bone marrow affected in thalassaemia?
The bone marrow expands to produce extra RBCs to compensate for the chronic anaemia.
This causes a susceptibility to fractures and prominent features, such as a pronounced forehead and malar eminences (cheek bones).
Signs & symptoms of thalassaemia?
- Microcytic anaemia
- Fatigue
- Pallor
- Jaundice
- Gallstones
- Splenomegaly
- Poor growth and development
- Pronounced forehead and malar eminences
Investigations in thalassaemia?
1) FBC: microcytic anaemia
2) Haemoglobin electrophoresis: used to diagnose globin abnormalities
3) DNA testing: can be used to look for the genetic abnormality
Screening for thalassaemia?
Pregnant woman offered screening test at booking visit.
Management of thalassaemia?
Repeated transfusion
What is a key complication of repeated transfusion in thalassaemia?
Iron overload –> organ failure.
Iron chelation therapy is therefore important (e.g. desferrioxamine)
Iron overload in thalassaemia causes effects similar to haemochromatosis.
What are some symptoms?
- Fatigue
- Liver cirrhosis
- Infertility
- Impotence
- Heart failure
- Arthritis
- Diabetes
- Osteoporosis and joint pain
Beta thalassaemia minor vs intermedia vs major?
Minor –> carriers of an abnormally functioning beta globin gene i.e. they have one abnormal and one normal gene.
Intermedia –> have two abnormal copies of the beta globin gene (can be either two defective genes or one defective gene and one deletion gene).
Major –> homozygous for the deletion genes i.e. have no functioning beta globin genes at all.
Give 3 complications of thalassaemia major?
1) Severe microcytic anaemia
2) Splenomegaly
3) Bone deformities
What can potentially be curative in thalassaemia?
Bone marrow transplant
What is hereditary spherocytosis?
A condition where the RBCs are sphere shaped, making them fragile and easily destroyed when passing through the spleen.
What is the most common inherited haemolytic anaemia in NORTHERN Europeans?
Hereditary spherocytosis
Inheritance of hereditary spherocytosis?
Autosomal dominant
Presentation of hereditary spherocytosis?
- Jaundice
- Anaemia
- Gallstones
- Splenomegaly
Patients can have episodes of haemolytic crisis.
What is this?
These are often triggered by infections, where the haemolysis, anaemia and jaundice is more significant.
Patients with hereditary spherocytosis can develop aplastic crisis.
What happens during aplastic crisis?
There is ncreased anaemia, haemolysis and jaundice, without the normal response from the bone marrow of creating new RBC.
Usually the bone marrow will respond to haemolysis by producing red blood cells faster, demonstrated by extra reticulocytes (immature red blood cells) in the blood. In aplastic crisis there is no reticulocyte response.
What is aplastic crisis in hereditary spherocytosis typically preceeded by?
Infection with parvovirus
What is seen on a blood film in hereditary spherocytosis?
Spherocytes
How is the mean corpuscular haemoglobin concentration (MCHC) affected in hereditary spherocytosis?
Raised MCHC
Reticulocytes in hereditary spherocytosis?
Raised
