The sickle cell anemia test is a blood test that helps doctors diagnose sickle cell anemia, a type of sickle cell disease (SCD). People of any age can have the test, but it is commonly part of newborn screening.
Doctors test for sickle cell anemia because babies with the condition have an increased risk of serious infections in the weeks after birth. Adults can also pass the condition to their offspring.
Sickle cell testing involves looking at an individual’s blood to determine whether they have
Keep reading to learn more about the sickle cell anemia test and what it involves.
SCDs are inherited blood disorders that cause changes to hemoglobin, a protein within the red blood cells. The red blood cells become misshapen, sticky, and inflexible. As a result, they can become stuck in the small blood vessels and cause blockages. These blockages can disrupt the blood and oxygen supply to the tissues, leading to serious health complications.
Doctors order a blood test to screen for sickle cell disease.
Sickle cell tests check for the presence of abnormal hemoglobin S (HbS) and can help doctors diagnose SCD.
Some tests a doctor may use to check for SCD
- a complete blood count (CBC)
- hemoglobin electrophoresis, which measures the levels of different hemoglobin types in the blood
- high performance liquid chromatography, which also identifies different hemoglobin types in the blood
- DNA testing, which can help identify people who may be carriers of the disease
Doctors may use a CBC to check for anemia, a condition in which abnormal hemoglobin prevents enough oxygen from being delivered to the cells. The CBC should also include a mean corpuscular volume (MCV) examination, which looks at the size of the red blood cells.
Learn more about the symptoms of SCD here.
When should people take this test?
In the United States, sickle cell testing is part of
Early testing helps prevent serious infections in infants with SCD.
Doctors may also test for the condition while the baby is in the womb by taking a sample of the placenta or amniotic fluid.
If someone did not have sickle cell testing as a child and is experiencing symptoms of the condition, they may require sickle cell testing.
SCD worsens over time, but treatments can prevent complications and help people with SCD live longer. Therefore, people should know their SCD status.
Additionally, because SCD is an inherited condition, people should know their status because they may risk passing the condition to their children.
If someone has sickle cell trait, it means they carry the gene for sickle cell disease but usually
Risk factors for sickle cell anemia
Sickle cell anemia passes from parents to children. Therefore, anyone who has a parent with sickle cell anemia is at risk.
People from certain racial or ethnic groups have an increased risk of sickle cell anemia, including:
- people of African descent
- people of Middle Eastern, Asian, Indian, or Mediterranean descent
- Hispanic Americans from Central and South America
A healthcare professional takes a blood sample. They place an elastic band around the upper arm to help enlarge the vein and then insert a small needle into the vein near the inner elbow.
The blood naturally flows into the syringe or vacuum tube attached to the needle. When the healthcare professional has enough blood, they remove the needle and cover the tiny puncture wound with a bandage.
Newborn babies undergo a heel stick test instead of a blood draw. This involves cleaning the heel with alcohol and piercing it with a small needle. The healthcare professional then collects the blood on a slide or test strip.
The sickle cell test is a standard blood test with very few risks.
A person may experience slight pain where the needle enters the vein, and the area may bruise. However, these symptoms typically resolve quickly.
The individual may feel lightheaded or dizzy after the blood test, but this can be temporary.
The blood analysis looks for HbS, a form of hemoglobin that leads to sickle-shaped red blood cells that cannot carry oxygen as they should. If a person has HbS in their blood, they develop sickle cell disease.
Normal results vs. abnormal results
A normal result is negative and means that the individual does not have the gene for sickle cell trait and does not have sickle cell disease.
If the screening test is positive, doctors usually order further tests to help determine which condition the individual has. If they have one mutated gene, they may have sickle cell trait, but if both genes are abnormal, they may have sickle cell disease.
In people with sickle cell trait, around 20–40% of the hemoglobin is HbS. In sickle cell disease, this increases to as much as 80–100%.
The National Collegiate Athletic Association (NCAA) recommends that athletic departments and colleges confirm the sickle cell status of their student-athletes.
During intense exercise, the sickle cells can block typical blood flow and cause serious complications. Between 2000 and 2009, seven student-athletes with sickle cell trait died during training.
Understanding someone’s sickle cell trait status enables coaches to take precautions but does not mean that coaches should exclude the students from athletics.
If the sickle cell test detects abnormal hemoglobin, a laboratory may perform further tests to analyze the types of hemoglobin present in the blood. These can
- Isoelectric focusing (IEF): This is a high resolution method for separating proteins using a pH gradient. It requires highly trained medical personnel to interpret the results but is the
standard testfor newborn screening. The test can detect certain hemoglobin types, such as HbA and HbS.
- High performance liquid chromatography (HPLC): This is a widely used method that can detect most hemoglobin types. It is a precise technique that allows scientists to quantify some of the different hemoglobin types in the red blood cells.
- Capillary electrophoresis (CE): This test uses an electrical charge to separate the different types of hemoglobin. It is also able to relatively quantify some hemoglobin types.
People should ask their doctor about sickle cell testing if they have any concerns.
A doctor may order the test if they consider it necessary.
A person can also contact the Sickle Cell Disease Association of America to find further information on testing locations.
Sickle cell testing involves taking a sample of blood and examining the hemoglobin within the red blood cells to help doctors diagnose sickle cell diseases. A sickle cell test is part of standard newborn screening tests in the U.S.
It is important for people to know their sickle cell status because the disease can cause serious health complications and people can pass the condition to their offspring.