Beta Thalassemia Differential Diagnoses

Updated: Dec 19, 2018
  • Author: Pooja Advani, MD; Chief Editor: Emmanuel C Besa, MD  more...
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DDx

Diagnostic Considerations

A major diagnostic consideration is to distinguish mild microcytic anemia due to beta-thalassemia carrier state from microcytic anemia due to other causes. Iron studies (iron, transferrin, ferritin) are useful in excluding iron deficiency and the anemia of chronic disorders as the cause of the patient's anemia.

Calculation of the Mentzer index (mean corpuscular volume per red cell count) may be helpful. A Mentzer index of less than 13 suggests that the patient has the thalassemia trait, and an index of more than 13 suggests that the patient has iron deficiency. [8]

Alpha thalassemia, which is characterized by genetic defects in the alpha-globin gene, is another known cause of mild microcytic anemia and has features similar to those of beta thalassemia. However, in contrast to beta-thalassemia minor (carrier) patients who have elevated levels of Hb A2 (2 alpha-globin chains complexed with 2 delta-globin chains), patients with alpha-thalassemia have normal levels of Hb.

Establishing the diagnosis of the alpha-thalassemia trait is often a diagnosis of exclusion. Definitive diagnosis requires measuring either the alpha-beta chain synthesis ratio or performing genetic tests of the alpha-globin cluster (using Southern blot or polymerase chain reaction [PCR] assay tests).

Unstable Hb levels and some types of red cell membrane disorders are other conditions to consider in the differential diagnosis of beta-thalassemia.

Differential Diagnoses