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Red Cell Disorders
 
 

Beta Thalassaemia

 
 
 
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Overview

Beta thalassaemia is an inherited defect in beta globin chains of haemoglobin, resulting in defective haemoglobin synthesis.
Beta thalassaemia is common in people from Mediterranean countries, South East Asia and India. It is rarely seen in those of caucasian descent.

Classification

GenotypePhenotype
Beta Thalassaemia Minor / Traitβ / Î²â°
β / β⁺
Mild or no anaemia with marked microcytosis
Beta Thalassaemia Intermediaβ⁺ / β⁺
β⁺ / β⁰
Moderate microcytic hypochromic anaemia
Beta Thalassaemia Majorβ⁰ / β⁰
Severe microcytic hypochromic anaemia
Bone marrow expansion
Iron overload
  • β - normal beta chains
  • β⁺ - reduced production of beta chains
  • β⁰ - no production of beta chains

Pathogenesis

Due to the lack of beta chains, there is an increase in haemoglobin Aâ‚‚ (consisting of two alpha and two delta chains) and haemoglobin F (foetal haemoglobin, consisting of two delta and two gamma chains).
An excess of alpha chains, combined with ineffective haemoglobin production, lead to ineffective red cell production and shorted red cell lifespan. The resulting anaemia stimulates erythropoietin release and further red cell production, eventually producing bone marrow expansion and iron overload.

Manifestations

Beta thalassaemia minor / trait tends to be asymptomatic, while beta thalassaemia intermedia and major may present with significant signs and symptoms.
  • Clinical Features of Beta Thalassaemia

  • Symptoms of anaemia - fatigue, lethargy, lightheadedness, shortness of breath, chest pain, headache
  • Jaundice: yellow discolouration of the skin
  • Hepatomegaly: enlarged liver
  • Splenomegaly: enlarged spleen
  • Beta Thalassaemia Major

  • Iron overload - hypogonadotrophic hypogonadism, hypothyroidism, hypoparathyroidism, diabetes mellitus, liver cirrhosis, heart failure
  • Bone marrow expansion - bony deformities, osteoporosis, muscle wasting

Diagnosis

  • Test Findings in Beta Thalassaemia

  • Full Blood Count & Film

  • Microcytic hypochromic anaemia
  • Poikilocytosis - target cells, teardrop cells, elliptocytes, fragments
  • Basophilic stippling
  • Nucleated red cells
  • Other Tests

  • High performance liquid chromatography / haemoglobin electrophoresis - increased haemoglobin Aâ‚‚ and haemoglobin F
  • Iron studies - elevated ferritin, elevated transferrin saturation (beta thalassaemia major)
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