Hemoglobin Electrophoresis

What is hemoglobin electrophoresis?

Hemoglobin is the protein inside red blood cells that carries oxygen from the lungs to the tissues. In adults, most hemoglobin is hemoglobin A (HbA); smaller proportions consist of hemoglobin A2 (HbA2) and fetal hemoglobin (HbF), the type that predominates before birth. Because of inherited differences, these proportions may change, or hemoglobins with a different structure, such as HbS, HbC, HbD or HbE, may appear.

Hemoglobin electrophoresis separates these hemoglobin types from one another and determines the proportion of each. Today, many laboratories use high-performance liquid chromatography (HPLC) or capillary electrophoresis. The report gives the hemoglobin fractions as percentages and separately notes the presence of any abnormal hemoglobin.

When is hemoglobin electrophoresis ordered?

The test is most often ordered when a complete blood count shows small red blood cells (low MCV) that cannot be explained by iron deficiency. Because thalassemia carrier status is relatively common in Türkiye, the test also plays an important role in premarital and preconception assessments. Since a child of two carriers may have a severe hemoglobin disorder, this information guides family planning.

• Small-cell (microcytic) anemia that cannot be explained by iron deficiency
• Premarital or preconception carrier screening
• A family history of thalassemia, sickle cell disease or another hemoglobin disorder
• Pallor or jaundice together with unexplained changes in the complete blood count
• Treatment monitoring in people diagnosed with a hemoglobin disorder
• Unexplained anemia in infancy or childhood

How should you prepare for hemoglobin electrophoresis?

Because the proportions of hemoglobin types do not change with meals, there is no fasting requirement for this test and you can choose any time of day. If you have had a blood transfusion in the last few months, the test may need to be postponed, as hemoglobin from the transfused blood can confuse the results; be sure to mention this. Because marked iron deficiency can lower the HbA2 proportion and mask beta thalassemia carrier status, your doctor may also order ferritin or iron tests at the same time. As some proportions may change slightly during pregnancy, it is also helpful to mention if you are pregnant.

A small amount of blood drawn from an arm vein into a purple-top tube containing EDTA is enough for the test. To interpret the result, a complete blood count is often run on the same sample as well. The sample can be taken by a nurse at your home or workplace in a short procedure that takes a few minutes.

What does the hemoglobin electrophoresis result mean?

A raised HbA2 proportion usually suggests beta thalassemia carrier status; carriers mostly have no symptoms and do not need treatment. A raised HbF may be associated with beta thalassemia, hereditary persistence of fetal hemoglobin or certain other conditions. Detection of a variant such as HbS calls for further evaluation for sickle cell trait or disease. Severe hemoglobin disorders usually cause marked anemia and require regular medical follow-up.

Alpha thalassemia carrier status often gives a normal result on this test, and genetic testing may be needed for a definitive diagnosis. Because HbF is naturally high in newborns and infants, results are interpreted differently according to age. Age, sex and the method used can affect the proportions considered normal; this page shows the HbA2 and HbF ranges of the laboratory that performs the test. Your result should be evaluated by a doctor together with your complete blood count, iron status and symptoms.