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updated April 01, 2009

Sickle cell anemia

Filed under: Boomer's Health
Sickle cell anemia is an inherited form of anemia — a condition in which there aren't enough healthy red blood cells to carry adequate oxygen throughout your body.

Normally, your red blood cells are flexible and round, moving easily through your blood vessels. In sickle cell anemia, the red blood cells become rigid, sticky and are shaped like sickles or crescent moons. These irregularly shaped cells can get stuck in small blood vessels, which can slow or block blood flow and oxygen to parts of the body.

There's no cure for most people with sickle cell anemia. However, treatments can relieve pain and help prevent further problems associated with sickle cell anemia.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Signs and symptoms of sickle cell anemia usually show up after an infant is 4 months old and may include:

  • Anemia. Sickle cells are fragile. They break apart easily and die, leaving you chronically short on red blood cells. Red blood cells usually live for about 120 days before they die and need to be replaced. However, sickle cells die after only 10 to 20 days. The result is a chronic shortage of red blood cells, known as anemia. Without enough red blood cells in circulation, your body can't get the oxygen it needs to feel energized. That's why anemia causes fatigue.
  • Episodes of pain. Periodic episodes of pain, called crises, are a major symptom of sickle cell anemia. Pain develops when sickle-shaped red blood cells block blood flow through tiny blood vessels to your chest, abdomen and joints. Pain can also occur in your bones. The pain may vary in intensity and can last for a few hours to a few weeks. Some people experience only a few episodes of pain. Others experience a dozen or more crises a year. If a crisis is severe enough, you may need hospitalization so that pain medication can be injected into your veins (intravenously).
  • Hand-foot syndrome. Swollen hands and feet may be the first signs of sickle cell anemia in babies. The swelling is caused by sickle-shaped red blood cells blocking blood flow out of their hands and feet.
  • Jaundice. Jaundice is a yellowing of the skin and eyes that occurs because of liver damage or dysfunction. Occasionally, people who have sickle cell anemia have some degree of jaundice because the liver, which filters harmful substances from the blood, is overwhelmed by the rapid breakdown of red blood cells. In people with dark skin, jaundice is visible mostly as yellowing of the whites of the eyes.
  • Frequent infections. Sickle cells can damage your spleen, an organ that fights infection. This may make you more vulnerable to infections. Doctors commonly give infants and children with sickle cell anemia antibiotics to prevent potentially life-threatening infections, such as pneumonia.
  • Delayed growth. Red blood cells provide your body with the oxygen and nutrients you need for growth. A shortage of healthy red blood cells can slow growth in infants and children and delay puberty in teenagers.
  • Vision problems. Some people with sickle cell anemia experience vision problems. Tiny blood vessels that supply your eyes may become plugged with sickle cells. This can damage the retina — the portion of the eye that processes visual images.

When to see a doctor
Although sickle cell anemia is usually diagnosed in infancy, if you or your child develops any of the following problems, see your doctor right away or seek emergency medical care.

  • Any signs or symptoms of stroke. If you notice any one-sided paralysis or weakness in the face, arms or legs, confusion, trouble walking or talking, sudden vision problems or numbness or a headache call 911 or your local emergency number right away.
  • Swelling in the hands or feet.
  • Abdominal swelling, especially if the area is tender to touch.
  • Fever. People with sickle cell anemia have an increased risk of infection, and fever can be the first sign of an illness.
  • Pale skin or nail beds.
  • Yellow tint to the skin or the whites of the eyes.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Sickle cell anemia is caused by a mutation in the gene that tells your body to make hemoglobin — the red, iron-rich compound that gives blood its red color. Hemoglobin is a component of every red blood cell. It allows red blood cells to carry oxygen from your lungs to all parts of your body, and to carry carbon dioxide waste from throughout your body to your lungs so that it can be exhaled.

Under normal circumstances, your body makes healthy hemoglobin known as hemoglobin A. People with sickle cell anemia make hemoglobin S — the S stands for sickle.

The sickle cell gene is passed from generation to generation in a pattern of inheritance called autosomal recessive inheritance. This means that both the mother and the father must pass on the defective form of the gene for a child to be affected.

People with sickle cell trait have one normal hemoglobin gene and one defective form of the gene. So their bodies make both normal hemoglobin and sickle cell hemoglobin. Their blood may contain some sickle cells, but they generally don't experience symptoms. However, they are carriers of the disease, which means they can pass the defective gene on to their children.

With each pregnancy, two people with sickle cell traits have:

  • A 25 percent chance of having an unaffected child with normal hemoglobin
  • A 50 percent chance of having a child who also is a carrier
  • A 25 percent chance of having a child with sickle cell anemia

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

The risk of inheriting sickle cell anemia comes down to genetics. For a baby to be born with sickle cell anemia, both parents must carry a sickle cell gene.

The gene is particularly common among people with African, Spanish, Mediterranean, Middle Eastern and Indian ancestry. In the United States, it most commonly affects blacks and Hispanics.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Sickle cell anemia can lead to a host of complications, including:

  • Stroke. A stroke can occur if sickle cells block blood flow to an area of your brain. Stroke is one of the most serious complications of sickle cell anemia. Signs of stroke include seizures, weakness or numbness of your arms and legs, sudden speech difficulties, and loss of consciousness. If your baby or child has any of these signs and symptoms, seek medical treatment immediately. A stroke can be fatal.
  • Acute chest syndrome. This life-threatening complication of sickle cell anemia causes chest pain, fever and difficulty breathing. Acute chest syndrome can be caused by a lung infection or by sickle cells blocking blood vessels in your lungs. It requires emergency medical treatment with antibiotics, blood transfusions and drugs that open up airways in your lungs. Recurrent attacks can damage your lungs.
  • Pulmonary hypertension. About one-third of people with sickle cell anemia will eventually develop high blood pressure in their lungs (pulmonary hypertension). Shortness of breath and difficulty breathing are common symptoms of this condition, which can ultimately lead to heart failure.
  • Organ damage. Sickle cells can block blood flow through blood vessels, immediately depriving an organ of blood and oxygen. In sickle cell anemia, blood is also chronically low on oxygen. Chronic deprivation of oxygen-rich blood can damage nerves and organs in your body, including your kidneys, liver and spleen. Organ damage can be fatal.
  • Blindness. Tiny blood vessels that supply your eyes can get blocked by sickle cells. Over time, this can damage the retina — the portion of the eye that processes visual images — and lead to blindness.
  • Skin ulcers. Sickle cell anemia can cause open sores, called ulcers, on your legs.
  • Gallstones. The breakdown of red blood cells produces a substance called bilirubin. Bilirubin is responsible for yellowing of the skin and eyes (jaundice) in people with sickle cell anemia. A high level of bilirubin in your body can also lead to gallstones.
  • Priapism. Men with sickle cell anemia may experience painful erections, a condition called priapism. As occurs in other parts of the body, sickle cells can block the blood vessels in the penis. This can damage the penis and eventually lead to impotence.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Sickle cell anemia is usually diagnosed through genetic screening done when a baby is born. Those test results will likely be given to your family doctor or pediatrician. However, if sickle cell anemia is diagnosed you'll probably then be referred to a doctor who specializes in blood disorders (hematologist) or a pediatric hematologist.

Because appointments can be brief, and there's often a lot of ground to cover, it's a good idea to be well prepared for your appointment. Here's some information to help you get ready, and what to expect from your doctor.

What you can do

  • Write down any symptoms you've noticed, including any that may seem unrelated to the reason for which you scheduled the appointment.
  • Bring a family member or friend along, if possible. Sometimes it can be difficult to remember all the information provided during an appointment. Someone who accompanies you may remember something that you missed or forgot.
  • Write down questions to ask your doctor.

Your time with your doctor is limited, so preparing a list of questions can help you make the most of your time together. List your questions from most important to least important in case time runs out. For sickle cell anemia, some basic questions to ask your doctor include:

  • What's the most likely cause of my child's symptoms?
  • Are there other possible causes?
  • What kinds of tests are needed?
  • What treatments are available, and which do you recommend?
  • What types of side effects are common with these treatments?
  • Are there any alternatives to the primary approach that you're suggesting?
  • What's my child's prognosis?
  • Are there any dietary or activity restrictions?
  • Are there any brochures or other printed material that I can take with me? What Web sites do you recommend?

In addition to the questions that you've prepared, don't hesitate to ask questions during your appointment at any time that you don't understand something.

What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over points you want to spend more time on. Your doctor may ask:

  • When did you first notice these symptoms?
  • Have they been continuous, or occasional?
  • Does anything seem to improve these symptoms?
  • What, if anything, appears to worsen the symptoms?
  • Does anyone in your family have sickle cell anemia?
  • Have you ever been told you have a trait for sickle cell anemia?

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

A blood test can check for hemoglobin S — the defective form of hemoglobin that underlies sickle cell anemia. In the United States, this blood test is part of routine newborn screening done at the hospital. But older children and adults can be tested too.

In adults, a blood sample is drawn from a vein in the arm. In young children and babies, the blood sample is usually collected from a finger or heel. The sample is then sent to a laboratory, where it's screened for hemoglobin S.

If the screening test is negative, there is no sickle cell gene present. If the screening test is positive, further tests will be done to determine whether one or two sickle cell genes are present. People who have one gene — sickle cell trait — have a fairly small percentage of hemoglobin S. People with two genes — sickle cell disease — have a much larger percentage of the defective hemoglobin.

Additional tests
To confirm any diagnosis, a sample of blood is examined under a microscope to check for large numbers of sickle cells — a marker of the disease. If you or your child has the disease, a blood test to check for anemia — a low red blood cell count — will be done. And your doctor may suggest additional tests to check for possible complications of the disease.

If you or your child carries the sickle cell gene, you may be referred to a genetic counselor — an expert in genetic diseases.

Sickle cell anemia can be diagnosed in an unborn baby by sampling some of the fluid surrounding the baby in the mother's womb (amniotic fluid) to look for the sickle cell gene.

Once diagnosed with sickle cell anemia, your child will need to see his or her doctor more often than most children do. For children under 2, ask your child's doctor how frequently checkups need to be scheduled. For youngsters over age 2, at least two visits a year are usually scheduled.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Bone marrow transplant offers the only potential cure for sickle cell anemia. But, finding a donor is difficult and the procedure has serious risks associated with it, including death.

As a result, treatment for sickle cell anemia is usually aimed at avoiding crises, relieving symptoms and preventing complications. If you have sickle cell anemia, you'll need to make regular visits to your doctor to check your red blood cell count and monitor your health. Treatments may include medications to reduce pain and prevent complications, blood transfusions and supplemental oxygen, as well as bone marrow transplant.

Medications
Medications used to treat sickle cell anemia include:

  • Antibiotics. Children with sickle cell anemia usually begin taking the antibiotic penicillin when they're about 2 months of age and continue taking it until they're 5 years old. Doing so helps prevent infections, such as pneumonia, which can be life-threatening to an infant or child with sickle cell anemia. Antibiotics may also help adults with sickle cell anemia fight certain infections.
  • Pain-relieving medications. To relieve pain during a sickle crisis, your doctor may advise over-the-counter pain relievers and application of heat to the affected area. You may also need stronger prescription pain medication.
  • Hydroxyurea (Droxia, Hydrea). This prescription drug, normally used to treat cancer, may be helpful for adults with severe disease. When taken daily, it reduces the frequency of painful crises and may reduce the need for blood transfusions. It seems to work by stimulating production of fetal hemoglobin — a type of hemoglobin found in newborns that helps prevent the formation of sickle cells. There is some concern about the possibility that long-term use of this drug may cause tumors or leukemia in certain people. Your doctor can help you determine if this drug may be beneficial for you.

Assessing stroke risk
Using a special ultrasound machine (transcranial), doctors can learn which children have a higher risk of stroke. This test can be used on children as young as 2, and those who are found to have a high risk of stroke are then treated with regular blood transfusions.

Blood transfusions
In a red blood cell transfusion, red blood cells are removed from a supply of donated blood. These donated cells are then given intravenously to a person with sickle cell anemia.

Blood transfusions increase the number of normal red blood cells in circulation, helping to relieve anemia. In children with sickle cell anemia at high risk of stroke, regular blood transfusions can decrease their risk of stroke.

Blood transfusions carry some risk. Blood contains iron. Regular blood transfusions cause an excess amount of iron to build up in your body. Because excess iron can damage your heart, liver and other organs, people who undergo regular transfusions must often receive treatment to reduce iron levels. Deferasirox (Exjade) is an oral medication that can reduce excess iron levels. It can be used in people older than 2.

Supplemental oxygen
Breathing supplemental oxygen through a breathing mask adds oxygen to your blood and helps you breathe easier. It may be helpful if you have acute chest syndrome or a sickle cell crisis.

Bone marrow transplant
This procedure replaces bone marrow affected by sickle cell anemia with healthy bone marrow from a donor who doesn't have the disease. It can be a cure, but the procedure is risky, and it's difficult to find suitable donors. Researchers are still studying bone marrow transplants for people with sickle cell anemia. Currently, the procedure is recommended only for people who have significant symptoms and problems from sickle cell anemia.

Bone marrow transplant requires a lengthy hospital stay. After the transplant, you'll need drugs to help prevent rejection of the donated marrow.

Treating complications
Doctors treat most complications of sickle cell anemia as they occur. Treatment may include antibiotics, vitamins, blood transfusions, pain-relieving medicines, other medications and possibly surgery, such as to correct vision problems or to remove a damaged spleen.

Experimental treatments
Scientists continue to gain new insights into the symptoms and causes of sickle cell anemia. Some possible new treatments being studied include:

  • Gene therapy. Because sickle cell anemia is caused by a defective gene, researchers are exploring whether inserting a normal gene into the bone marrow of people with sickle cell anemia will result in the production of normal hemoglobin. Scientists are also exploring the possibility of turning off the defective gene while reactivating another gene responsible for the production of fetal hemoglobin — a type of hemoglobin found in newborns that prevents sickle cells from forming.
  • Butyric acid. Normally used as a food additive, butyric acid may increase the amount of fetal hemoglobin in the blood.
  • Clotrimazole. This over-the-counter antifungal medication helps prevent a loss of water from red blood cells, which may reduce the number of sickle cells that form.
  • Nitric oxide. Sickle cell anemia causes low levels of nitric oxide, a gas that helps keep blood vessels open and reduces the stickiness of red blood cells. Treatment with nitric oxide may prevent sickle cells from clumping together.
  • Nicosan. This is an herbal treatment in early trials in the U.S. Nicosan has been used to prevent sickle crises in Nigeria.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Taking steps to stay healthy is critical for anyone with sickle cell anemia. Eating well, getting adequate rest and protecting yourself from infections are good ways to maintain your health and prevent crises.

Infants and children with sickle cell disease need to receive regular childhood vaccinations. Children and adults with sickle cell anemia also should have a yearly flu shot and be immunized against pneumonia.

If you or your child has sickle cell anemia, follow these suggestions to help stay healthy:

  • Take folic acid supplements daily, and eat a balanced diet. Bone marrow needs folic acid and other vitamins to make new red blood cells.
  • Drink plenty of water. Staying hydrated helps keep your blood diluted, which reduces the chance that sickle cells will form.
  • Avoid temperature extremes. Exposure to extreme heat or cold can trigger the formation of sickle cells.
  • Reduce stress. A sickle crisis can occur as a result of stress.
  • Exercise regularly, but don't overdo it. Talk with your doctor about how much exercise is right for you.
  • Use over-the-counter medications with caution. Some medications, such as the decongestant pseudoephedrine, can constrict your blood vessels and make it harder for the sickle cells to move through freely.
  • Fly on airplanes with pressurized cabins. Unpressurized aircraft cabins may not provide enough oxygen. Low oxygen levels can trigger a sickle crisis. Additionally, be sure to drink extra water when traveling by air, as pressurized cabins can be dehydrating.
  • Avoid high-altitude areas. Traveling to a high-altitude area may also trigger a crisis because of lower oxygen levels.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

If you or someone in your family has sickle cell anemia, you may want help with the stresses of this lifelong disease. Sickle cell centers and clinics can provide information and counseling. Ask your doctor or the staff at a sickle cell center if there are support groups for families in your area. Talking with others who are facing the same challenges you are can be helpful.

It's especially important to find ways to control — and cope with — pain. Different techniques work for different people, but it might be worth trying heating pads, hot baths, massages or physical therapy. Prayer, family and friends also can be sources of support.

If you have a child with sickle cell anemia, learn as much as you can about the disease and make sure your child gets the best health care possible. A child with sickle cell disease has special needs and requires regular medical care. Your doctor can explain how often to bring your child for medical care and what you can do if he or she becomes ill.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

If you carry the sickle cell trait, you may wish to see a genetic counselor before trying to conceive a child. A genetic counselor can help you understand your risk of having a child with sickle cell anemia. He or she can also explain possible treatments, preventive measures and reproductive options.

There is an in vitro fertilization procedure that improves the chances for parents who both carry the sickle cell gene to have a child with normal hemoglobin. This procedure is known as preimplantation genetic diagnosis. First, eggs are taken from the mother. Then, sperm is taken from the father. In a laboratory, the eggs are fertilized with the sperm. The fertilized eggs are then tested for the presence of the sickle cell gene. Fertilized eggs free of the sickle cell gene can be implanted into the mother for normal development. However, this procedure is expensive and not always successful.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

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