hydroxyurea

Sickle cell disease (SCD) is a group of inherited red blood cell disorders. If you have SCD, there is a problem with your hemoglobin. Hemoglobin is a protein in red blood cells that carries oxygen throughout the body. With SCD, the hemoglobin forms into stiff rods within the red blood cells. This changes the shape of the red blood cells. The cells are supposed to be disc-shaped, but this changes them into a crescent, or sickle, shape.

The sickle-shaped cells are not flexible and cannot change shape easily. Many of them burst apart as they move through your blood vessels. The sickle cells usually only last 10 to 20 days, instead of the normal 90 to 120 days. Your body may have trouble making enough new cells to replace the ones that you lost. Because of this, you may not have enough red blood cells. This is a condition called anemia, and it can make you feel tired.

The sickle-shaped cells can also stick to vessel walls, causing a blockage that slows or stops the flow of blood. When this happens, oxygen can't reach nearby tissues. The lack of oxygen can cause attacks of sudden, severe pain, called pain crises. These attacks can occur without warning. If you get one, you might need to go to the hospital for treatment.

The cause of SCD is a defective gene, called a sickle cell gene. People with the disease are born with two sickle cell genes, one from each parent.

If you are born with one sickle cell gene, it's called sickle cell trait. People with sickle cell trait are generally healthy, but they can pass the defective gene on to their children.

In the United States, most of the people with SCD are African Americans:

• About 1 in 13 Black or African American babies are born with sickle cell trait
• About 1 in every 365 Black or African American babies are born with sickle cell disease

SCD also affects some people who come from Hispanic, southern European, Middle Eastern, or Asian Indian backgrounds.

People with SCD start to have signs of the disease during the first year of life, usually around 5 or 6 months of age. Early symptoms of SCD may include:

• Painful swelling of the hands and feet
• Fatigue or fussiness from anemia
• A yellowish color of the skin (jaundice) or the whites of the eyes (icterus)

The effects of SCD vary from person to person and can change over time. Most of the signs and symptoms of SCD are related to complications of the disease. They may include severe pain, anemia, organ damage, and infections.

A blood test can show if you have SCD or sickle cell trait. All states now test newborns as part of their screening programs, so treatment can begin early.

People who are thinking about having children can have the test to find out how likely it is that their children will have SCD.

Health care providers can also diagnose SCD before a baby is born. That test uses a sample of amniotic fluid (the liquid in the sac surrounding the baby) or tissue taken from the placenta (the organ that brings oxygen and nutrients to the baby).

Treatments for SCD include:

• Bone marrow or stem cell transplantation, which can cure SCD. Because these transplants are risky and can have serious side effects, they are usually only used in children with severe SCD. For the transplant to work, the bone marrow must be a close match. Usually, the best donor is a brother or sister.
• Gene therapies to treat SCD in people who are 12 years and older and have had repeated sickle cell crises. These new therapies involve taking some of your blood stem cells and either adding new DNA to them or changing their existing DNA. Then these cells are given back to you, and they can make a type of hemoglobin that is healthy. This can reduce the complications of SCD, including the SCD crises.
• Treatments that can help relieve symptoms and lessen complications, including:
  • Antibiotics to try to prevent infections in younger children
  • Pain relievers for acute or chronic pain
  • Hydroxyurea, a medicine that has been shown to reduce or prevent several SCD complications. It increases the amount of fetal hemoglobin in the blood. This medicine is not right for everyone; talk to your provider about whether you should take it. This medicine is not safe during pregnancy.
  • Blood transfusions for severe anemia. If you have had some serious complications, such as a stroke, you may have transfusions to prevent more complications.
  • Other treatments for specific complications, such as medicines to lower blood pressure and vitamins to treat a vitamin deficiency.

To stay as healthy as possible, make sure that you:

• Get regular medical care
• Get your routine vaccinations
• Live a healthy lifestyle
• Avoid situations that may set off a pain crisis

NIH: National Heart, Lung, and Blood Institute