What is sickle cell anemia?

Sickle cell anemia is an inherited disease that causes abnormal red blood cells. It is a lifelong disease starting at birth.

Sickle cell disease is most prevalent among people who are African, African American, Mediterranean (Italian, Sicilian, Greek), middle Eastern, East Indian, Caribbean, and Central or South American. In the U.S. the frequency of sickle cell anemia among African Americans is about one in every 400 births. About 50,000 African Americans have sickle cell disease. One of every twelve African American newborns carries the sickle cell trait in his or her genes.

How does it occur?

Sickle cell anemia is inherited. A baby will have sickle cell anemia if both the mother and the father are carriers of the gene for sickle cell anemia. A parent can be a carrier of just one copy of the gene and not have the disease. However, if a child inherits a sickle cell trait gene from each parent, the child has two copies of the gene and will have sickle cell anemia.

The red blood cells carry oxygen from your lungs to the rest of your body. A chemical in the red blood cells called hemoglobin helps the cells carry oxygen. If you have sickle cell anemia, most of your red blood cells contain an abnormal type of hemoglobin called hemoglobin S. This abnormal hemoglobin makes the red blood cells more easily damaged by changes in your body. They may become distorted or be destroyed by:

• a viral infection, especially one that affects the lungs

• a fever

• dehydration (loss of too much body fluid)

• a decrease in available oxygen or a change in air pressure, both of which can happen on an airplane.

These changes in your body change the shape of the sensitive red blood cells from a normal round, disklike shape to a lazy-S or sickle shape. This shape makes the red blood cells unable to carry oxygen. The sickle-shaped cells can also get stuck in the bloodstream and form clots. These clots and the decrease in normal red blood cells make it difficult for all parts of your body to get enough oxygen.

What are the symptoms?

The first symptoms of sickle cell disease usually do not appear until a child is about a year old. The first symptoms are often brought on by a viral infection. They may include fever, swelling of the hands and feet, and joint or abdominal pain.

Toddlers and children may have frequent pain with or without any physical signs of illness.

Most children and adults with sickle cell anemia have periods of no symptoms (called remissions) between crises. Crises are the times when the abnormal red blood cells form clots. The most common symptom of a sickle cell crisis is pain. The pain is usually felt in the part of the body where the sickling cells are causing thickening and clotting of the blood.

Sickle cell anemia can cause your skin to appear pale as the anemia worsens. The paleness may be most obvious on the inside of your eyelids, under fingernails, and in the creases of the palms of your hands. Your skin may also turn yellow (jaundiced).

One of the life-threatening complications of sickle cell disease can be sudden, severe anemia. This severe shortage of normal red blood cells may cause weakness, shortness of breath, or even heart failure. The symptoms of shock caused by heart failure are low blood pressure, rapid pulse, and decreasing consciousness.

How is it diagnosed?

Sickle cell anemia should be diagnosed as early as possible. The ideal test for diagnosis is hemoglobin electrophoresis. This blood test detects sickle cell hemoglobin S. It can also be used to find carriers of the sickle cell trait.

A complete blood count (CBC) is done to confirm the effects or complications of sickle cell anemia. The red blood cells are counted under a microscope and checked for abnormal shapes.

How is it treated?

People with sickle cell anemia are more likely to have serious infections ranging from flu to pneumonia. Prevention of serious infections is an important part of the treatment in sickle cell anemia. To help prevent infections you should:

• Make sure all of your immunizations are up to date.

• Get a flu shot every year.

• Get the pneumococcus vaccine (a one-time shot) to protect against a common type of pneumonia.

• Check with your health care provider about other possible vaccines, including hepatitis A and B, chickenpox, and meningococcus vaccine.

• Take antibiotics to prevent infections if prescribed by your health care provider.

• Take a daily multiple vitamin to help your body make new red blood cells.

• Contact your health care provider whenever you become sick, even with minor illnesses. You may be given IV fluids (to prevent dehydration) and oxygen, which in turn help prevent sickling of the red blood cells.

If you have a sickle cell crisis, you will be given IV fluids and pain medication. You will need to rest. So many red blood cells may be destroyed during the crisis that you may need a blood transfusion.

What are the complications of sickle cell anemia?

Because abnormal red blood cells are circulating throughout your body, complications can occur in any part of your body. Frequently occurring problems include:

• infections such as pneumonia or meningitis

• kidney infections

• bone infections

• gallstones

• poorer vision from damage to blood vessels in the eyes

• hip and shoulder joint damage

• stroke

• damage to tissues in the penis, called priapism (when sickling occurs in the penis, the tissues can become engorged from time to time, sometimes resulting in impotence).

How can sickle cell anemia be prevented?

Sickle cell anemia can be prevented if couples who both carry the sickle cell trait gene do not have children. When both parents are carriers, each child has a 25% risk of having sickle cell anemia and a 50% risk of being a carrier.

Screening tests can be used to find carriers. Couples who find that they are carriers should seek genetic counselling.