Beta-Thalassemia Testing and Complications

By Dr Ananya Mandal, MD

There are three forms of beta thalassemia that vary in severity and symptom onset and these are described below:

Thalassemia major

Individuals with thalassemia major usually develop symptoms within the first two years of life. These infants may fail to thrive and often have difficulty feeding, tire easily and suffer from severe anemia.

The infants may also suffer from diarrhea, irritability, recurrent episodes of fever, and other intestinal problems. These children have trouble gaining weight and growing at the rate expected for their age. Other complications include enlarged spleen, heart and liver and misshapen bones.

In many cases, the symptoms are severe enough to warrant regular blood transfusion to replenish the blood with healthy red blood cells. However, these regular transfusions can lead to a build up of iron in the blood that can damage the heart, liver and endocrine system and chelation therapy may be needed to remove this iron from the body.

Beta thalassemia intermedia

The symptoms of thalassemia intermedia are milder than those of thalassemia major and often manifest later in life. Such individuals may have mild to moderate anemia and growth abnormalities. Often patients do not require transfusions when they are younger but may need to start them when they are older.

Beta thalassemia minor

This form of thalassemia usually gives rise to mild symptoms but patients do not require blood transfusion. Although this condition is not life threatening, quality of life may be affected by mild-to-moderate anemia. This form of the condition is also referred to as beta thalassemia trait.

Diagnosis

Beta thalassemia is diagnosed based on various different tests which include:

Blood tests

In cases of beta thalassemia, the red blood cells appear small (microcytic) and pale (hypochromic), compared to those seen on normal blood smears. The red blood cells may also be nucleated, an indication that they are immature forms (also known as erythroblasts).

In thalassemia major, the hemoglobin (Hb) level is usually less than 7 g/dl; the mean corpuscolar volume (MCV) less than 70 fl and the mean corpuscolar Hb (MCH) is over 20 pg.

In thalassemia intermedia, the hemoglobin level is between 7 and 10 g/dl; the MCV between 50 and 80 fl and MCH between 16 and 24 pg.

Thalassemia minor is characterized by a reduced MCV and MCH and an increased haemoglobin A2 level.

Molecular genetic analysis

DNA analysis can be performed to check for mutations in the genes that code for the beta globin chains found in hemoglobin. The test is not usually carried out routinely but may be performed in cases where a physician suspects the condition based on signs and symptoms such as anemia, breathlessness and the results of blood tests. DNA analysis can help diagnose the condition as well as determining carrier status in other members of the family.

Complications

Some of the complications associated with beta thalassemia (especially thalassemia major) include:

  • Enlargement of the spleen increases the risk of injury and rupture of the organ which can be life threatening. An enlarged spleen also presses against other vital organs, in which case it may need to be removed in a procedure called a splenectomy. Since the spleen plays an important part in fighting infection, a splenectomy can result in an increased risk of infection.
  • Liver complications include hepatitis, enlarged liver or scarring of the liver (cirrhosis).
  • Affected bone marrow and bone deformities increase the risk of joint pain, osteoporosis and susceptibility to fracture.
  • Other complications include pulmonary hypertension (high blood pressure within the blood vessels of the lungs), thromboembolic complications and sepsis after splenectomy.
  • Blood transfusion is also associated with complications. Regular transfusions can increase the risk of iron overload which can lead to complications such as:
    • Hormonal disturbances - Iron overload can disrupt the endocrine system and balance of hormones, which can result in hypogonadism (low functioning of the genital and reproductive organs), infertility, underactive thyroid and diabetes. The secretion of growth hormone may also be impaired and retard growth.
    • Liver damage and fibrosis
    • Heart damage and disease

Reviewed by , BSc

Sources

  1. http://www.nhs.uk/conditions/Thalassaemia/Pages/Introduction.aspx
  2. http://www.cooleysanemia.org/updates/pdf/Beta_Thalassemia.pdf
  3. http://www.biomedcentral.com/content/pdf/1750-1172-5-11.pdf
  4. http://www.doh.wa.gov/Portals/1/Documents/5220/BetaThal.pdf
  5. http://www.thalassaemia.org.au/resources/factsheets/vic/vic%20beta_fact%20sheet_2.pdf

Further Reading

Last Updated: Feb 17, 2014

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