Thalassaemia Flashcards
What is thalassaemia?
Genetic defect in protein chains that make up Hb
What protein chains is normal Hb made of?
2 alpha and 2 beta globin chains
What is an alpha vs beta thalassaemia?
Alpha - defect in alpha globin chains
Beta - defect in beta globin chains
Both are autosomal recessive conditions
What happens to RBCs in patients with thalassaemia?
More fragile and break down more easily
Why do patients with thalassaemia get splenomegaly?
Spleen collects all the destroyed RBCs
How is chronic anaemia due to thalassaemia compensated for?
Bone marrow expands to produce extra RBCs
What does bone marrow expansion lead to?
Increased susceptibility to fractures
Pronounced forehead
Pronounced malar eminences
What are the potential signs of thalassaemia?
Microcytic anaemia
Pallor
Jaundice
Gallstones
Splenomegaly
Poor growth and development
Pronounced forehead and malar eminences
Fatigue
How is thalassaemia diagnosed?
- FBC - shows microcytic anaemia
- Haemoglobin electrophoresis - diagnose globin abnormalities
- DNA testing - genetic abnormality
Pregnant women offered screening test for thalassaemia at booking
Why does iron overload occur in thalassaemia?
- Faulty RBC synthesis
- Recurrent transfusions
- Increased iron absorption in gut in response to anaemia
How are patients with thalassaemia monitored?
Serum ferritin levels to check for iron overload
How is iron overload managed?
Limit transfusions
Iron chelation
What does iron overload cause?
Fatigue
Liver cirrhosis
Infertility
Impotence
Heart failure
Arthritis
Diabetes
Osteoporosis and joint pain
What is given for iron chelation?
Desferrioxamine
What is alpha-thalassaemia caused by?
Autosomal recessive gene mutation on chromosome 16 which codes for alpha globin chains
How is alpha thalassaemia managed?
- Monitor FBC
- Monitor complications
- Blood transfusions
- Splenectomy
- Bone marrow transplant - may be curative
Outline alpha-thalassaemia major
Deletion of 4 α-globulin genes
Not compatible with life as foetus cannot produce globin chains to form Hb
How does α-thalassaemia present on antenatal scans?
Bart’s hydrops fetalis
Polyhydramnios
Increased nuchal translucency
What is beta-thalassaemia caused by?
Autosomal recessive gene mutation on chromosome 11 which codes for beta globin chains
Gene defect can have abnormal copies that retain some function or deletion genes where there is no function in the beta globin protein at all
How is beta-thalassaemia split?
Thalassaemia minor
Thalassaemia intermedia
Thalassaemia major
What is thalassaemia minor?
Abnormally functioning beta globin gene
One abnormal and one normal gene
Causes mild microcytic anaemia, patient only needs monitoring and no treatment
What is thalassaemia intermedia?
Two abnormal beta globin gene copies
Two defective
or
One defective and one deletion gene
Causes significant microcytic anaemia
Require monitoring and occasional blood transfusions
May need iron chelation to prevent iron overload when giving blood transfusions
What is thalassaemia major?
Homozygous for deletion genes
No functioning beta globin genes at all
Most severe form
Why are patients at increased risk of fractures in thalassemia major?
Bone marrow expands so much to compensate it increases fracture risk
How does thalassaemia major present?
Severe anaemia
Failure to thrive
What does thalassaemia major cause?
Severe microcytic anaemia
Splenomegaly
Bone deformities
What bone deformities does thalassaemia major cause?
Frontal bossing
Enlarged maxilla
Depressed nasal bridge
Protruding upper teeth
How is thalassaemia major managed?
Regular transfusions
Iron chelation
Splenectomy
Bone marrow transplant can be curative
What do patients with splenectomy need?
Daily Penicillin V
Vaccination
- Pneumococcus every 5 years
- Flu every year
Give erethromycin in penicillin allergy
What causes raised HbA1c in splenectomy patients?
Long red-cell lifespan
Hb has increased amount of time to become glycosylated
Causes raised HbA1c without any diabetes symptoms
