Beta Thalassaemia- Microcytic Anaemia Flashcards
1
Q
What is the typical Haemoglobin type?
A
- HbA (Two alpha and two beta)
2
Q
What is the genetic inheritance of Beta Thalassaemia?
A
- Autosomal Recessive
3
Q
What are the types of Beta Thalassaemia?
A
- Beta Thalassaemia minor
- Beta Thalassaemia intermedia
- Beta Thalassaemia major
4
Q
How does Beta thalassaemia minor present?
A
- One abnormal beta globin chain. Typically asymptomatic with mild anaemia.
5
Q
How does Beta thalassaemia intermedia present?
A
- mutation in both genes leading to abnormal beta globin chains
- Non- transfusion dependant
6
Q
How does Beta thalassaemia major present?
A
- mutation in both genes leading to patients with absent beta globin chain production
- Transfusion dependant
7
Q
When is Beta thalassaemia major typically seen?
A
- Typically presents after 6 months of age
- ## When there is a change from foetal haemoglobin to adult haemoglobin (HbF to HbA)
8
Q
What is the pathophysiology of beta thalassaemia major?
A
- Imbalance in the alpha and beta chains
- Ineffective erythropoiesis - (formation of new red blood cells)
- Haemolysis in the bone marrow and peripheral blood supply
- Reduced red blood cell survival
- Increased iron absorption leading to overload
- Chronic transfusion-dependant anaemia
9
Q
What is extramedullary haematopoiesis?
A
- Haematopoiesis occurring outside the medulla of the long bones.
- Typical sites include: spleen, liver and unusual bones
- Increase in haematopoiesis makes no difference as there is a lack of beta globin chains
- Increased production of HbA2 and HbF
- However, this increased production can not meet the demands of the body
- Excessive Alpha chains leads to formation of unstable alpha tetramers
10
Q
What is the summary of the pathophysiology of beta thalassaemia?
A
- Haemolysis
- Extramedullary haematopoiesis
- Iron Overload
11
Q
What are the clinical manifestations of Beta Thalassaemia?
A
- Anaemia
- Jaundice
- Skeletal Changes: - Facial Deformity (frontal bossing, prominent upper incisors, chipmunk facies), body habitus changes (short limbs), osteoporosis, boney pain
- Iron Overload ( increase in iron absorption from GI with regular blood transfusions = Iron chelation therapy is required)
- Other abnormalities: Pulmonary ( obstructive/ restrictive defects - pulmonary hypertension), Thrombotic (increased hypercoagulable state), Leg Ulcers
12
Q
What Initial testing is required for beta thalassaemia?
A
- FBC (low hb, low MCV, RBC increased and low reticulocyte count)
- Blood Film (hypochromic, microcytic RBC)
- LFTs (unconjugated hyperbilirubinaemia)
- Haemolysis Screen (LDH)
- Iron Studies
13
Q
What Diagnostic testing is avaliable?
A
- Haemoglobin analysis ( Haemoglobin electrophoresis - shows increased proportion of HbA2 and HbF)
- Genetic Testing
- Anenatal Screening is also avaliable
14
Q
What is the management of beta thalassaemia?
A
- Chronic Blood transfusions: every 2/3 week, extended cross-matching to prevent alloimmunisation (development of an immune response to red blood cell antigens)
- Iron Overload and Chelation therapy: Iron levels need to be monitored using ferritin and MRI imaging to visualise depositions in organs (hepatic and cardiac in particular)
- Iron Chelation therapy required (Deferasirox and Deferoxamine) these bind to iron and increase the excretion through urine
- Splenectomy may be considered in patients with symptomatic splenomegaly
15
Q
What is the prognosis for a patient with beta thalassaemia major
A
- Reduced life expectancy
