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Sickle Cell Disease

What is sickle cell disease?

Sickle cell disease is an inherited disorder of the red blood cells. Normally, red blood cells are soft, round, and smooth (like donuts) and they slide through blood vessels easily. They are made up of a protein called hemoglobin A (HbA). Hemoglobin transports oxygen throughout the body.

However, in sickle cell disease, the hemoglobin inside the red blood cell makes the cell into a sickle shape (like a half-moon). These hard, sickle-shaped cells get stuck in blood vessels and block blood flow. This abnormal hemoglobin in red blood cells is known as hemoglobin S (HbS) or sickle hemoglobin.

Over 80,000 children in the United States have sickle cell disease. It is more common in people whose families come from African, Asian, Middle Eastern, or Mediterranean countries.

What are the signs and symptoms of sickle cell disease?

The primary symptom of sickle cell disease is pain. Pain can last for a few moments to several days. Other symptoms include: fatigue (tiredness), breathlessness, rapid heart rate, delayed growth, fever, yellow eyes or skin, or priapism (painful erections). Serious complications of sickle cell disease include stroke, gallbladder stones, damage to the retina (a part of the eye), and high blood pressure of the lungs.

Sickled cells carry less oxygen for tissues, stick together, and cause blockage of blood flow. This blockage prevents even more oxygen from reaching the tissues that need it. Damage can occur to the brain, lungs, chest, spleen, bones, and eyes. Studies show that the more painful episodes a child has each year, the more likely a child will have long-term disabilities.

What causes a sickle cell crisis?

Although sickled cells clog blood vessels, there are several things that contribute to making sickle cell worse, such as infections, dehydration, emotional stress, extreme temperatures, alcohol, or drugs.

What is sickle cell trait?

Some people do not have sickle cell disease, but they do have sickle cell trait. This means there is both normal hemoglobin (HbA) and sickle hemoglobin (HbS) present in the blood. Usually, enough normal hemoglobin is produced to keep the red cells flexible and round. This is why people with sickle cell trait rarely have health problems.

How does a person get sickle cell disease?

Sickle cell disease is inherited from parents similar to the way physical traits, like hair color, are inherited from parents. The types of hemoglobin a person makes in the red blood cells depend upon what hemoglobin genes the person inherits from his or her parents. Like most genes, hemoglobin genes are inherited in two sets (one from each parent). To inherit the disease, a child must receive two sickle cell genes, one from each parent.

For example:

  • If one parent has sickle cell disease and the other is normal, all of the children will have sickle cell trait.
  • If one parent has sickle cell disease and the other has sickle cell trait, there is a 50% chance (or 1 out of 2) of having a baby with either sickle cell disease or sickle cell trait with each pregnancy.
  • When both parents have sickle cell trait, they have a 25% chance (1 of 4) of having a baby with sickle cell disease with each pregnancy.

Source: Sickle Cell Disease Association of America

How is sickle cell disease diagnosed?

A simple blood test helps to determine the type of hemoglobin a person has. In babies, it is generally diagnosed by newborn screening tests required under state law. Because children with sickle cell disease are at an increased risk of infection and other health complications, early diagnosis and treatment is important. Currently, more than 48 states have newborn screening programs for sickle cell disease.

Why is it important to have regular check-ups?

Yearly check-ups help your health care provider ensure that your child is in the best of health. It gives both you and the provider a chance to ask questions and to keep an eye on how sickle cell disease is affecting your child's body and your child's everyday life. At these visits, your provider will review the blood tests and screening results, as well as update your child's immunizations. Blood tests check red cells, white cells, and platelets as well as liver and kidney function. Annual vision screening and Transcranial Doppler (TCD) imaging look at the health of the eyes and brain.

What annual screenings are needed?

Vision: Long before patients even notice symptoms, sickled cells can clog and damage tiny blood vessels in the eyes. If the blood vessels are severely damages, this can cause blindness. It is important that patients have yearly vision exams by a professional - specifically, a professional who is familiar with sickle cell disease (not just someone who can prescribe glasses). Eye exams should start around 3 years of age.

Transcranial Doppler (TCD) Imaging: Sickled cells can also cause damage in blood vessels of the brain. Injured blood vessels here can cause strokes and permanent brain damage. Small strokes can occur in teenagers and even very young children. TCD imaging shows how fast the blood flows through the vessels that feed the brain. Abnormal results help your provider to adjust your medical care to keep you as healthy as possible. TCD imaging should start around 2 years of age and does not hurt. It only takes about 30 minutes to perform. Smaller patients can even sit on a parent's lap during the procedure.

Immunizations: The spleen helps the immune system to fight disease and keep you healthy. However, in many sickle cell patients, the spleen no longer works. Without a working spleen, patients not only get sicker more easily (and more frequently), but they also stay sicker for longer periods of time. One easy way to avoid more serious illness is to keep on schedule with all immunizations, including a yearly flu shot in the fall.

How is sickle cell disease treated?

Health maintenance for patients with sickle cell disease starts with early diagnosis. Patients are best managed in a comprehensive multidisciplinary program of care.

Medicines are available to help manage the pain of a sickle cell crisis and help prevent infection. Most doctors also prescribe daily vitamin supplements for children with sickle cell disease. Folic acid, in particular, helps the body to produce new red blood cells.

Children with sickle cell disease who develop complications (such as acute chest syndrome, severe anemia, or stroke) may receive regular transfusions of red blood cells to prevent or treat these complications. Treatment of complications may also include antibiotics, pain management, or intravenous fluids.


Hydroxyurea is a drug that helps reduce the number and intensity of painful episodes and complications in patients with sickle cell disease. In 1998, the U.S. Food and Drug Administration (FDA) approved the use of hydroxyurea in patients 18 years and older. It has not yet been FDA approved for use in children, but studies are underway to determine the proper dosage, efficacy, and safety for children and infants. Some of our patients have participated in these studies and our doctors are experienced in the use of hydroxyurea for select patients. Other treatment options being developed include more convenient options to eliminate iron overload caused by repeated blood transfusions.

Cleveland Clinic Children's

Cleveland Clinic Children's provides World Class Care to children and adolescents with complex blood disorders. In continuing our efforts to provide excellent care, we have developed a comprehensive Sickle Cell Clinic. This Clinic is led by Dr. Kate Gowans and Denis Davis, PNP, RN. The ultimate goal of this service is to minimize hospitalizations and complications for our patients through preventive care and education.

The Department of Pediatric Hematology/Oncology is open Monday through Friday 8 am - 5 pm. Most patients with sickle cell disease are seen on Tuesday afternoons; however, for fever, pain, vomiting, or other signs of illness, patients are encouraged to call for an immediate appointment. Both the Sickle Cell Clinic and the Department of Pediatric Hematology/Oncology can be reached at 216.444.5517.

Should you have more questions about the child or young adult in your life with a blood disorder, please contact the Cleveland Clinic Cancer Answer line at 216.444.3024 or 800.223.2273, extension 4-3024. We wish you and your child well.

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This information is provided by the Cleveland Clinic Health System and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. Rev. 08/06

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