hemoglobin electrophoresis
Summary
Hemoglobin electrophoresis is a laboratory technique that separates hemoglobin variants based on their charge and mobility in an electric field, used primarily to diagnose hemoglobinopathies such as sickle cell disease and thalassemias. It quantifies percentages of HbA, HbA2, HbF, HbS, HbC, and other variants.
Detail
Hemoglobin electrophoresis works by applying an electric current to a sample of hemolyzed red blood cells on a gel or cellulose acetate medium (or using capillary electrophoresis/HPLC in modern labs). Hemoglobin variants migrate at different rates based on their net surface charge, which is altered by amino acid substitutions (e.g., glutamic acid to valine in HbS). This allows separation and quantification of normal hemoglobin (HbA), fetal hemoglobin (HbF), HbA2, and abnormal variants like HbS (sickle cell), HbC, HbE, and others.
Clinical significance: Used to diagnose sickle cell disease (HbSS - mostly HbS, no HbA), sickle cell trait (HbAS - HbA and HbS present), and various thalassemia syndromes (elevated HbA2 and/or HbF in beta-thalassemia). Essential for newborn screening programs, prenatal diagnosis, and evaluating unexplained hemolytic anemia or abnormal CBC findings (microcytic anemia not explained by iron deficiency).
Key associations: - HbS: sickle cell disease/trait (single point mutation, β6 Glu→Val) - HbC: milder hemolytic disease, target cells - HbA2 elevation: beta-thalassemia trait - HbF elevation: beta-thalassemia major, hereditary persistence of fetal hemoglobin - Combined hemoglobinopathies (e.g., HbSC disease, HbS/beta-thalassemia) can be identified
Limitations: Cannot detect all hemoglobin variants (some have identical migration patterns); alpha-thalassemia often shows normal electrophoresis (requires genetic testing). Often paired with CBC, peripheral smear, and iron studies for complete workup. High-performance liquid chromatography (HPLC) is increasingly replacing traditional gel electrophoresis due to better resolution and quantification.
Sources
- First Aid for the USMLE Step 1
- Robbins Basic Pathology
- Harrison's Principles of Internal Medicine
- UpToDate: Diagnosis of hemoglobinopathies
Reviewed by AnkiBoss editorial — medical student review. Information here is for study reference only and is not medical advice. Spotted an error? Let us know.