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Hemoglobin electrophoresis is a test that aims to identify the different types of hemoglobin that can be found circulating in the blood.
Hemoglobin or Hb is a protein present in red blood cells responsible for binding oxygen, allowing transport to tissues. Learn more about hemoglobin.
From the identification of the type of hemoglobin, it is possible to verify if the person has any disease related to the synthesis of hemoglobin, such as thalassemia or sickle cell anemia, for example. However, to confirm the diagnosis, it is necessary to perform other hematological and biochemical tests.
What is it for
Hemoglobin electrophoresis is requested to identify structural and functional changes related to hemoglobin synthesis. Thus, this exam may be recommended by the doctor in the following situations:
- Diagnosis of sickle cell anemia;
- Diagnosis of hemoglobin C disease;
- Differentiation of thalassemia types;
- Routine examination in people who have already been diagnosed with changes in hemoglobin.
In addition, hemoglobin electrophoresis can also be requested in order to genetically advise couples who wanted to have children, being informed if there is a chance that the child has any type of blood disorder related to hemoglobin synthesis. In the case of newborn babies, the identification of the type of hemoglobin is done through the heel prick test, which is important for the diagnosis of sickle cell anemia.
How it's made
Hemoglobin electrophoresis is a simple test performed from a blood sample collected by a trained professional in a specialized laboratory, because incorrect collection can result in hemolysis, that is, destruction of red blood cells, which can interfere with the result.
The collection must be performed with the patient fasting for at least 4 hours and the sample sent for analysis in the laboratory, in which the types of hemoglobin present in the patient are identified. In some laboratories, fasting is not necessary for collection. Therefore, it is important to seek guidance from the laboratory and the doctor about fasting for the exam.
How to understand the results
In the result of the hemoglobin electrophoresis, the types of hemoglobin that the person has and in what concentration are indicated. It is considered normal when the person has hemoglobin A1, in higher concentration, and A2.In infants, fetal hemoglobin (HbF) is present in higher concentrations, however, as development proceeds, HbF concentrations decrease while HbA1 increases.
Thus, the concentrations of each type of hemoglobin vary according to age, being normally:
|Hemoglobin type||Normal value|
|HbF||1 to 7 days old: up to 84%;
8 to 60 days old: up to 77%;
2 to 4 months old: up to 40%;
4 to 6 months old: up to 7.0%
7 to 12 months of age: up to 3.5%;
12 to 18 months of age: up to 2.8%;
Adult: 0.0 to 2.0%
|HbA1||Equal to or greater than 95%|
|HbA2||1, 5 - 3, 5%|
However, some people have structural or functional alterations related to hemoglobin synthesis, resulting in abnormal or variant hemoglobins, such as HbS, HbC, HbH and Barts' Hb.
Changes in hemoglobin type
Thus, from hemoglobin electrophoresis, it is possible to identify the presence of abnormal hemoglobins and, with the aid of another diagnostic technique, it is possible to verify the concentration of normal and abnormal hemoglobins, which may be indicative of:
- Presence of HbSS: Sickle cell anemia, which is characterized by a change in the shape of the red blood cell due to a mutation in the beta chain of hemoglobin. Know the symptoms of sickle cell anemia.
- Presence of HbAS: Sickle cell trait, in which the person carries the gene responsible for sickle cell anemia, but does not have symptoms, however, this gene can be passed on to other generations:
- Presence of HbC: Indicative of Hemoglobin C disease, in which HbC crystals can be seen in the blood smear, especially when the patient is HbCC, in which the person has variable degree hemolytic anemia.
- Presence of Barts Hb: The presence of this type of hemoglobin indicates a serious condition known as fetal hydrops, which can result in fetal death and consequent miscarriage. Learn more about hydrops fetalis.
- Presence of HbH: Indicative of Hemoglobin H disease, which is characterized by precipitation and extravascular hemolysis.
In the case of diagnosing sickle cell anemia by the heel prick test, the normal result is HbFA (that is, the baby has both HbA and HbF, which is normal), while the HbFAS and HbFS results are indicative of sickle cell trait and sickle cell anemia respectively.
To confirm the diagnosis of any disease related to hemoglobin, other tests such as iron, ferritin, transferrin, in addition to a complete blood count, must be requested. Here's how to interpret the blood count.