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To investigate hemoglobinopathy as the cause of signs and symptoms; to screen for a hemoglobin disorder
As follow up to abnormal results on a complete blood count (CBC) and/or blood smear; when you have symptoms of hemolytic anemia such as weakness and fatigue and your healthcare practitioner suspects that you have an abnormal form of hemoglobin (hemoglobinopathy); when you have a family history of hemoglobinopathy; as part of newborn screening
A blood sample drawn from a vein in your arm or obtained from the heel or finger of an infant
A hemoglobinopathy is an inherited blood disorder in which an individual has an abnormal form of hemoglobin (variant) or decreased production of hemoglobin (thalassemia). A hemoglobinopathy evaluation is a group of tests that determines the presence and relative amounts of abnormal forms of hemoglobin in order to screen for and/or diagnose a hemoglobin disorder.
Hemoglobin (Hb) is the iron-containing protein found in all red blood cells (RBCs) that binds to oxygen in the lungs and allows RBCs to carry the oxygen throughout the body, delivering it to the body's cells and tissues. Hemoglobin consists of one portion called heme, which is the molecule with iron at the center, and another portion made up of four globin (protein) chains. The globin chains, depending on their structure, have different designations: alpha, beta, gamma, and delta. The types of globin chains that are present are important in the function of hemoglobin and its ability to transport oxygen.
Normal hemoglobin types include:
Hemoglobinopathies occur when changes (mutations) in the genes that code for the globin chains cause alterations in the proteins. These genetic changes may result in a reduced production of one of the normal globin chains or in the production of structurally altered globin chains. Genetic mutations may affect the structure of the hemoglobin, its behavior, its production rate, and/or its stability. The presence of abnormal hemoglobin within RBCs can alter the appearance (size and shape) and function of the red blood cells.
Red blood cells containing abnormal hemoglobin (hemoglobin variants) may not carry oxygen efficiently and may be broken down by the body sooner than usual (a shortened survival), resulting in hemolytic anemia.
Some of the most common hemoglobin variants include:
Thalassemia is a condition in which a gene mutation results in reduced production of one of the globin chains. This can upset the balance of alpha to beta chains, leading to decrease in hemoglobin A, causing abnormal hemoglobin to form (alpha thalassemia) or causing an increase of minor hemoglobin components, such as Hb A2 or Hb F (beta thalassemia).
Many other less common hemoglobin variants exist. Some are silent – causing no signs or symptoms – while others affect the function and/or stability of the hemoglobin molecule.
To learn more about these conditions, read the articles on Hemoglobin Abnormalities and Thalassemia.
An investigation of a hemoglobin disorder typically involves tests that determine the types and amounts of hemoglobin present in a person's sample of blood. Information from these tests, along with results from routine tests such as a complete blood count (CBC) and blood smear, aid in establishing a diagnosis. To learn more, see the next section.
A hemoglobinopathy evaluation is used to detect abnormal forms and/or relative amounts of hemoglobin, the protein found in all red blood cells that transports oxygen. Testing may be used for:
Several different laboratory methods are available to evaluate the types of hemoglobin that a person has. Some of these include:
These methods evaluate the different types of hemoglobin based on the physical and chemical properties of the different hemoglobin molecules.
Most of the common hemoglobin variants or thalassemias can be identified using one of these tests or a combination. The relative amounts of any variant hemoglobin detected can aid in a diagnosis. However, a single test is usually not sufficient to establish a diagnosis of hemoglobinopathy. Rather, the results of several different tests are considered. Examples of other laboratory tests that may be performed include:
Testing for hemoglobinopathies is required as part of state-mandated newborn screening. In addition, it is often used for prenatal screening when a parent is at high risk or when parents have a child who has a hemoglobinopathy.
It may be ordered when a healthcare practitioner suspects that a person's signs and symptoms are the result of abnormal hemoglobin production. Abnormal forms of hemoglobin often lead to hemolytic anemia, resulting in signs and symptoms such as:
Some severe forms of hemoglobinopathies (e.g., sickle cell disease) may result in serious signs and symptoms, such as episodes of severe pain, shortness of breath, enlarged spleen, and growth problems in children.
Care must be taken when interpreting the results of a hemoglobinopathy evaluation. Typically, the laboratory report includes an interpretation by a pathologist with experience in the field of hematology (hematopathologist).
Results of the evaluation usually report the types of hemoglobin present and the relative amounts. For adults, percentages of normal hemoglobin include:
Some of the most common abnormal forms of hemoglobin that may be detected and measured with this testing include:
Some less common forms include:
Other types that may be identified include:
Testing may help identify thalassemia by detecting abnormal hemoglobin (e.g., hemoglobin H in alpha thalassemia) or an increase of minor hemoglobin components, such as Hb A2 or Hb F (beta thalassemia).
A person can also inherit two different abnormal genes, one from each parent, that may result in a combination of abnormal hemoglobins detected by testing. This is known as being compound heterozygous or doubly heterozygous. Clinically significant combinations — those that result in significant signs and symptoms — include hemoglobin SC disease, hemoglobin E – beta thalassemia, and hemoglobin S – beta thalassemia.
For more information on these conditions, see the articles on Hemoglobin Abnormalities and Thalassemia.
Some examples of results that may be seen with a hemoglobinopathy evaluation are listed in the following table.
|Slightly decreased Hb A
Moderate amount Hb S (about 40%)
|Sickle cell trait||One gene copy for Hb S (heterozygous)|
|Majority Hb S
Increased Hb F (up to 10%)
No Hb A
|Sickle cell disease||Two gene copies for Hb S (homozygous)|
|Majority Hb C
No Hb A
|Hemoglobin C disease||Two gene copies for Hb C (homozygous)|
|Majority Hb A
Some Hb H
|Hemoglobin H disease (alpha thalassemia)||Three out of four alpha genes are mutated (deleted)|
|Majority Hb F
Little or no Hb A
|Beta thalassemia major||Both beta genes are mutated|
|Majority Hb A
Slightly Increased Hb A2 (4-8%)
Hb F may be slightly increased
|Beta thalassemia minor||One beta gene is mutated, causing slight decrease in beta globin chain|
Blood transfusions can interfere with hemoglobinopathy evaluation. You should wait several months after a transfusion before having this testing done. However, in people with sickle cell disease, the testing may be performed after a transfusion to determine if enough normal hemoglobin has been given to reduce the risk of damage from sickling of red blood cells.
Newborn screening helps to identify potentially treatable or manageable congenital disorders within days of birth. Potentially life-threatening health problems and serious lifelong disabilities can be avoided or minimized if a condition is quickly identified and treated. Also, since newborn screening programs have mandated testing for hemoglobin variants, they have uncovered thousands of children who are carriers. (This is due to new technology, not to an increased prevalence of the gene mutations.) Information on carrier status may be important in their future if and when they begin to plan a family.
It depends on the method of testing and the laboratory performing the evaluation. This testing requires specialized equipment and not every laboratory performs this test. Your sample may be sent to a reference laboratory, so it may take several days before results are available.
Treatment for certain types of hemoglobin disorders may involve supportive care, for example during a sickle cell crisis. The aim is to relieve pain and minimize complications. Sometimes blood transfusions are needed if there is severe anemia. There are some other less common treatments that are available. For more information on these, see the articles on Hemoglobin Abnormalities and Thalassemia as well as the links listed in the Related Content section below.
Sources Used in Current Review
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Agarwal, A. et. al. (2017 February Updated). Hemoglobinopathies. ARUP Consult. Available online at https://arupconsult.com/content/hemoglobinopathies. Accessed on 02/18/17.
Maakaron, J. et. al. (2016 September 24, Updated). Anemia. Medscape Drugs and Diseases. Available online at http://emedicine.medscape.com/article/198475-overview#showall. Accessed on 02/18/17.
Inoue, S. et. al. (2016 April 12 Updated). Pediatric Chronic Anemia. Medscape Drugs and Diseases. Available online at http://emedicine.medscape.com/article/954598-overview. Accessed on 02/18/17.
(© 1995–2017). Hemoglobin Electrophoresis Cascade, Blood. Mayo Clinic Mayo Medical Laboratories. Available online at http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/81626 Accessed on 02/18/17.
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