How are thalassemias diagnosed?

Moderate and severe thalassemias are often diagnosed in childhood because symptoms usually appear during the first 2 years of a child's life.

Various blood tests are used to diagnose thalassemias:

  • A complete blood count (CBC), which includes measures of hemoglobin and the quantity (and size) of red blood cells. People with thalassemias have fewer healthy red blood cells and less hemoglobin than normal; those with alpha or beta thalassemia trait may have smaller-than-normal red blood cells.
  • A reticulocyte count (a measure of young red blood cells) may indicate that your bone marrow is not producing an adequate number of red blood cells.
  • Studies of iron will indicate whether the cause of the anemia is iron deficiency or thalassemia (iron deficiency is not the cause of anemia in people with thalassemias).
  • Hemoglobin electrophoresis is used to diagnose beta thalassemia.
  • Genetic testing is used to make a diagnosis of alpha thalassemia.

Last reviewed by a Cleveland Clinic medical professional on 07/14/2018.


  • National Heart, Lung, and Blood Institute. What Are Thalassemias? Accessed 3/5/2020.
  • Centers for Disease Control and Prevention. Thalassemia Accessed 3/5/2020.
  • American Academy of Family Physicians/ Thalassemia Accessed 3/5/2020.

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