Hemoglobin electrophoresis is an important test used to diagnose conditions such as sickle cell anemia and thalassemia, as it can detect structural and functional abnormalities in hemoglobin production.
Hemoglobin (Hb) is a protein in red blood cells that binds to oxygen and transports it throughout the body.
By identifying the different types of hemoglobin present, hemoglobin electrophoresis helps determine whether a person may have a disorder related to hemoglobin synthesis. However, confirmation of the diagnosis still requires additional hematologic and biochemical tests.
Indications for testing
Hemoglobin electrophoresis may be ordered for:
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Diagnosing sickle cell anemia;
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Diagnosing hemoglobin C disease;
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Differentiating between types of thalassemia;
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Routine monitoring in people who have already been diagnosed with hemoglobin abnormalities.
In addition, the hemoglobin electrophoresis test may be requested for genetic counseling in couples who want to have children, to determine whether there is a chance the child could have a blood disorder related to hemoglobin synthesis.
In newborns, hemoglobin type is typically identified through newborn screening (a heel stick test), which is important for diagnosing sickle cell anemia.
How the test is performed
Hemoglobin electrophoresis is a simple test done using a blood sample collected by a trained professional in a specialized lab. Improper collection can cause hemolysis (breakdown of red blood cells), which may affect the results.
In general, no special preparation is required and fasting is usually not needed. However, some laboratories may give specific instructions. For this reason, it is important to follow guidance from the lab and the healthcare provider about whether fasting is needed.
Interpreting the results
A hemoglobin electrophoresis report shows which types of hemoglobin a person has and their concentrations. Normal concentrations vary by age and are generally:
Some people have structural or functional changes related to hemoglobin synthesis, resulting in abnormal or variant hemoglobins, such as HbS, HbC, HbH, and Hb Barts.
Normal result
A result is considered normal when hemoglobin A1 is present in the highest concentration, along with hemoglobin A2. In babies, fetal hemoglobin (HbF) is present in higher concentrations. As the baby develops, HbF levels decrease while HbA1 levels increase.
Abnormal hemoglobins
Hemoglobin electrophoresis can identify the presence of abnormal hemoglobins. With the help of another diagnostic technique, it is also possible to determine the concentration of normal and abnormal hemoglobins. Findings may indicate:
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Presence of HbSS: Sickle cell anemia, which is characterized by a change in the shape of red blood cells due to a mutation in the beta chain of hemoglobin. Learn the ARTICLE NOT FOUND IN EN: symptoms of sickle cell anemia;
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Presence of HbAS: Sickle cell trait, in which a person carries the gene responsible for sickle cell anemia but does not have symptoms. However, the gene can be passed on to future generations;
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Presence of HbC: Suggestive of hemoglobin C disease. HbC crystals may be seen on a blood smear, especially in HbCC, in which the person has hemolytic anemia of varying severity;
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Presence of Hb Barts: This type of hemoglobin indicates a serious condition known as hydrops fetalis (fetal hydrops), which can result in fetal death and, consequently, miscarriage.
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Presence of HbH: Suggestive of hemoglobin H disease, which is characterized by precipitation and extravascular hemolysis.
When sickle cell anemia is screened through newborn screening, a normal result is HbFA (meaning the baby has both HbA and HbF, which is normal). Results of HbFAS and HbFS indicate sickle cell trait and sickle cell anemia, respectively.
To confirm the diagnosis of any hemoglobin-related condition, other tests are needed, such as iron, ferritin, and transferrin levels, as well as a complete blood count (CBC).