Hemoglobin Electrophoresis


Hemoglobin Electrophoresis

 

Definition

Hemoglobin electrophoresis (also called Hgb electrophoresis), is a test that measures the different types of hemoglobin in the blood. The method used is called electrophoresis, a process that causes movement of particles in an electric field, resulting in formation of "bands" that separate toward one end or the other in the field.

Purpose

Hgb electrophoresis is performed when a disorder associated with abnormal hemoglobin (hemoglobinopathy) is suspected. The test is used primarily to diagnose diseases involving these abnormal forms of hemoglobin, such as sickle cell anemia and thalassemia.

Precautions

Blood transfusions within the previous 12 weeks may alter test results.

Description

Hemoglobin (Hgb) is comprised of many different types, the most common being A1, A2, F, S, and C.Hgb A1 is the major component of hemoglobin in the normal red blood cell. Hgb A2 is a minor component of normal hemoglobin, comprising approximately 2-3% of the total.Hgb F is the major hemoglobin component in the fetus, but usually exists only in minimal quantities in the normal adult. Levels of Hgb F greater than 2% in patients over three years of age are considered abnormal.Hgb S is an abnormal form of hemoglobin associated with the disease of sickle cell anemia, which occurs predominantly in African-Americans. A distinguishing characteristic of sickle cell disease is the crescent-shaped red blood cell. Because the survival rate of this type of cell is limited, patients with sickle cell disease also have anemia.Hgb C is another hemoglobin variant found in African Americans. Red blood cells containing Hgb C have a decreased life span and are more readily destroyed than normal red blood cells, resulting in mild to severe hemolytic anemia.Each of the major hemoglobin types has an electrical charge of a different degree, so the most useful method for separating and measuring normal and abnormal hemoglobins is electrophoresis. This process involves subjecting hemoglobin components from dissolved red blood cells to an electric field. The components then move away from each other at different rates, and when separated form a series of distinctly pigmented bands. The bands are then compared with those of a normal sample. Each band can be further assessed as a percentage of the total hemoglobin, thus indicating the severity of any abnormality.

Preparation

This test requires a blood sample. No special preparation is needed before the test.

Risks

Risks for this test are minimal, but may include slight bleeding from the blood-drawing site, fainting or feeling lightheaded after venipuncture, or hematoma (blood accumulating under the puncture site).

Normal results

Normal reference values can vary by laboratory, but are generally within the following ranges.Adults:
  • Hgb A1: 95-98%
  • Hgb A2: 2-3%
  • Hgb F: 0.8-2.0%
  • Hgb S: 0%
  • Hgb C: 0%.
Child (Hgb F):
  • 6 months: 8%
  • greater than 6 months: 1-2%
  • newborn (Hgb F): 50-80%

Abnormal results

Abnormal reference values can vary by laboratory, but when they appear within these ranges, results are usually associated with the conditions that follow in parentheses.Hgb A2:
  • 4-5.8% (β-thalassemia minor)
  • under 2% (Hgb H disease)
Hgb F:
  • 2-5% (β-thalassemia minor)
  • 10-90% (β-thalassemia major)
  • 5-35% (Heterozygous hereditary persistence of fetal hemoglobin, or HPFH)
  • 100% (Homozygous HPFH)
  • 15% (Homozygous Hgb S)

Key terms

Hemoglobin C disease — A disease of abnormal hemoglobin, occurring in 2-3% of African-Americans. Only those who have two genes for the disease develop anemia, which varies in severity. Symptoms include episodes of abdominal and joint pain, an enlarged spleen and mild jaundice.Hemoglobin H disease — A thalassemia-like syndrome causing moderate anemia and red blood cell abnormalities.Heterozygous — Two different genes controlling a specified inherited trait.Homozygous — Identical genes controlling a specified inherited trait.Thalassemias — The name for a group of inherited disorders resulting from an imbalance in the production of one of the four chains of amino acids that make up hemoglobin. Thalassemias are categorized according to the amino acid chain affected. The two main types are alpha-thalassemia and betathalassemia. The disorders are further characterized by the presence of one defective gene (thalassemia minor) or two defective genes (thalassemia major). Symptoms vary, but include anemia, jaundice, skin ulcers, gallstones, and an enlarged spleen.Homozygous Hgb S:
  • 70-98% (Sickle cell disease).
Homozygous Hgb C:
  • 90-98% (Hgb C disease)

Resources

Books

Pagana, Kathleen Deska. Mosby's Manual of Diagnostic and Laboratory Tests. St. Louis: Mosby, Inc., 1998.

Hemoglobin Electrophoresis

Synonym/acronym: N/A.

Common use

To assist in evaluating hemolytic anemias and identifying hemoglobin variants, diagnose thalassemias, and sickle cell anemia.

Specimen

Whole blood (1 mL) collected in a lavender-top (EDTA) tube.

Normal findings

(Method: Electrophoresis)
Hgb A
AdultGreater than 95%
Hgb A2
Adult1.5–3.7%
Hgb F
Newborns and infants
 1 day–3 wk70–77%
 6–9 wk42–64%
 3–4 mo7–39%
 6 mo3–7%
 8–11 mo0.6–2.6%
Adult–older adultLess than 2%

Description

Hemoglobin (Hgb) electrophoresis is a separation process used to identify normal and abnormal forms of Hgb. Electrophoresis and high-performance liquid chromatography as well as molecular genetics testing for mutations can also be used to identify abnormal forms of Hgb. Hgb A is the main form of Hgb in the normal adult. Hgb F is the main form of Hgb in the fetus, the remainder being composed of Hgb A1 and A2. Small amounts of Hgb F are normal in the adult. Hgb D, E, H, S, and C result from abnormal amino acid substitutions during the formation of Hgb and are inherited hemoglobinopathies.

This procedure is contraindicated for

    N/A

Indications

  • Assist in the diagnosis of Hgb C disease
  • Assist in the diagnosis of thalassemia, especially in patients with a family history positive for the disorder
  • Differentiate among thalassemia types
  • Evaluate hemolytic anemia of unknown cause
  • Evaluate a positive sickle cell screening test to differentiate sickle cell trait from sickle cell disease

Potential diagnosis

Increased in

    Hgb A2

  • Hyperthyroidism
  • Megaloblastic anemia
  • β-Thalassemias
  • Sickle trait

    • Hgb F

  • Anemia (aplastic, associated with chronic disease or due to blood loss)
  • Erythropoietic porphyria
  • Hereditary elliptocytosis or spherocytosis
  • Hereditary persistence of fetal Hgb
  • Hyperthyroidism
  • Leakage of fetal blood into maternal circulation
  • Leukemia (acute or chronic)
  • Myeloproliferative disorders
  • Paroxysmal nocturnal hemoglobinuria
  • Pernicious anemia
  • Sickle cell disease
  • Thalassemias
  • Unstable hemoglobins

    • Hgb C

  • Hgb C disease (second most common variant in the United States; has a higher prevalence among African Americans)

    • Hgb D

  • Hgb D (rare hemoglobinopathy that may also be found in combination with Hgb S or thalassemia)

    • Hgb E

  • Hgb E disease; thalassemia-like condition (second most common hemoglobinopathy in the world; occurs with the highest frequency in Southeast Asians and African Americans)

    • Hgb S

  • Sickle cell trait or disease (most common variant in the United States; occurs with a frequency of about 8% among African Americans)

    • Hgb H

  • α-Thalassemias
  • Hgb Bart’s hydrops fetalis syndrome

Decreased in

    Hgb A2

    Erythroleukemia Hgb H disease Iron-deficiency anemia (untreated) Sideroblastic anemia

Critical findings

    N/A

Interfering factors

  • High altitude related to a compensatory mechanism whereby red blood cell (RBC) production is increased to increase availability of oxygen binding to Hgb and dehydration related to hemoconcentration may increase values.
  • Iron deficiency may decrease Hgb A2, C, and S related to decreased amounts of Hgb in smaller, iron-deficient RBCs.
  • In patients less than 3 mo of age, false-negative results for Hgb S occur in coincidental polycythemia related to technical limitations of the procedure where increased total Hgb levels reflect a small, possibly undetectable percentage of Hgb S when compared to large amounts of Hgb F.
  • Red blood cell transfusion within 4 mo of test can mask abnormal Hgb levels.

Nursing Implications and Procedure

Potential nursing problems

ProblemSigns & SymptomsInterventions
Health management (Related to excessive demands; support deficit; conflicted decision making; limited resources; sense of powerlessness)Inability or failure to recognize or process information toward improving health and preventing illness with associated mental and physical effectsAssess health habits to obtain an interventional baseline; obtain a current health history; identify the patient’s and family’s learning styles; refrain from using medical jargon; observe for altered literacy cues; provide most important information first and reinforce with additional education; ensure the patient understands the ramifications of a lack of healthy behaviors on sickling events; identify number of emergency department visits for sickling crises; instruct the patient and family on situations that can precipitate a crisis; recommend genetic counseling
Pain (Related to hypoxic vaso-occlusive crisis secondary to sickling disease)Emotional symptoms of distress; crying; agitation; facial grimace; moaning; verbalization of pain; rocking motions; irritability; disturbed sleep; diaphoresis; altered blood pressure and heart rate; nausea; vomiting; self-report of pain; limited mobilityCollaborate with the patient and physician to identify the best pain management modality to provide relief; refrain from activities that may aggravate pain; use the application of heat or cold to the best effect in managing the pain; monitor pain severity; assess sickle pain characteristics, location, type, and duration; monitor pain severity (severe joint pain, abdominal, or back pain may last for days); administer prescribed pain medication (typically IV morphine, hydromorphone, or fentanyl, NSAIDs); monitor HGB/HCT and transfuse with blood as ordered; use splinting of joints, joint support, moist heat to manage pain; consider distraction and rest periods
Coping (Related to sense of powerlessness secondary to sickling event; feeling loss of control; poor support system; chronic nature of the disease process)Anxiety; demonstrated inability to cope; poor problem solving; inability to meet role expectations; fatigue; frequent illness; poor goal-directed behavior; fear; difficulty asking for helpAssess the ability to convey feelings clearly and appropriately; assess presence and stability of support structure; evaluate number of emergency department visits with sickling events; discuss concerns with the patient at a time that the pain is controlled; provide education related to the treatment of and chronic nature of the disease; consult with social services and case management for home support and community resources
Mobility (Related to pain hypoxic vaso-occlusive crisis secondary to sickling disease)Difficulty in the performance of purposeful movement (walking, turning, transfers); pain with movement; reluctance or refusal to move; inability to perform directed movementAssess baseline ability to move; assess need for assistive devices, encourage appropriate use; assess pain level; assess pain medication effectiveness; administer prescribed pain medication; assess emotional response to mobility deficits; ensure a safe environment with side rail up; ensure that room is not cluttered; facilitate ambulation as appropriate; monitor for skin breakdown and deep vein thrombosis (DVT)

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this test can assist in diagnosing various types of anemias.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s hematopoietic system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Note any recent procedures that can interfere with test results.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.

Intratest

  • Potential complications: N/A
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
  • Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
  • Promptly transport the specimen to the laboratory for processing and analysis.

Post-Test

  • Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

  • Patient Education

    • Teach the patient that the frequency of sickling crises is reflective of disease control and need for review of therapeutic management.
    • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP.
    • Answer any questions or address any concerns voiced by the patient or family.
    • Teach patient and family the pathophysiology of sickle cell disease in understandable terms.

  • Expected Patient Outcomes

    • Knowledge
    • States understanding that the support of similar patients may assist with coping and disease management
    • States understanding that adherence to disease management recommendations can decrease sickling events
    • Skills
    • Describes lifestyle changes that can be made to decrease hypoxic episodes and the incidence of sickling crises
    • Identifies symptoms of infection that should be reported to the HCP
    • Attitude
    • Complies with the request for genetic counseling
    • Complies with recommended therapeutic management for sickle cell disease

Related Monographs

  • Related tests include biopsy bone marrow, blood gases, CBC, CBC hematocrit, CBC hemoglobin, CBC RBC morphology, methemoglobin, newborn screening, osmotic fragility, and sickle cell screen.
  • Refer to the Hematopoietic System table at the end of the book for related tests by body system.