From the Guidelines
To evaluate for thalassemia, DNA testing for specific anomalies, including alpha-thalassemia, should be performed if the mean corpuscular volume (MCV) of parents is less than 80 fL, as recommended by the Society for Maternal-Fetal Medicine 1. This approach is based on the fact that thalassemia is a genetic disorder affecting hemoglobin production, and DNA testing can identify specific mutations in the alpha or beta globin genes.
- The diagnostic approach is guided by the pattern of red blood cell indices, particularly the presence of microcytosis (low MCV) with normal or high red blood cell count, which is characteristic of thalassemia.
- Additional testing may include quantitative measurement of hemoglobin A2 and hemoglobin F levels, which are often elevated in beta thalassemia.
- Iron studies should also be included to differentiate thalassemia from iron deficiency anemia, as both conditions present with microcytic anemia but thalassemia typically shows normal or elevated iron levels.
- Family testing may be recommended since thalassemia is an inherited disorder, and the Society for Maternal-Fetal Medicine recommends considering DNA testing for alpha-thalassemia if the MCV is less than 80 fL 1.
- While other studies, such as the practice guidelines for the diagnosis and management of microcytic anemias due to genetic disorders of iron metabolism or heme synthesis, provide additional information on the diagnosis of microcytic anemias 1, the most recent and relevant guideline for thalassemia diagnosis is provided by the Society for Maternal-Fetal Medicine 1.
From the Research
Evaluation for Thalassemia
To evaluate for thalassemia, a genetic disorder affecting hemoglobin production, several tests can be used. The following are some of the key tests:
- Complete blood count (CBC) to identify microcytic hypochromic anemia 2, 3
- Hemoglobin electrophoresis or high-performance liquid chromatography (HPLC) to separate and measure hemoglobin fractions 2, 3
- Quantitation of HbA2 and HbF to help identify beta-thalassemia carriers 2, 3
- Serum ferritin to exclude iron deficiency anemia 2, 3
- Brilliant cresyl blue stained blood smear to identify H bodies in cases of alpha-thalassemia 2
- Molecular analysis, such as DNA testing, to confirm the diagnosis of alpha-thalassemia or to predict severe cases of thalassemia 3
Diagnostic Approach
The diagnostic approach for thalassemia typically involves a combination of these tests. For example:
- If a patient has microcytic anemia and normal or elevated ferritin levels, thalassemia should be suspected 4
- Hemoglobin electrophoresis may reveal common characteristics of different thalassemia subtypes, but genetic testing is required to confirm the diagnosis 4
- A combination of routine blood tests, serum iron, and hemoglobin electrophoresis can improve the detection efficiency of patients with thalassemia 5
Decision Support Systems
Decision support systems, such as those using machine learning algorithms, can also be used to distinguish between beta-thalassemia and iron deficiency anemia 6. These systems can analyze parameters such as hemoglobin, RBC, HCT, MCV, MCH, MCHC, and RDW to provide accurate diagnoses.