Sickle cell anemia

Sickle cell anemia is one of a group of inherited disorders known as sickle cell disease. It affects the shape of red blood cells, which carry oxygen to all parts of the body.

Red blood cells are usually round and flexible, so they move easily through blood vessels. In sickle cell anemia, some red blood cells are shaped like sickles or crescent moons. These sickle cells also become rigid and sticky, which can slow or block blood flow.

There's no cure for most people with sickle cell anemia. Treatments can relieve pain and help prevent complications associated with the disease.

Symptoms

Signs and symptoms of sickle cell anemia usually appear around 6 months of age. They vary from person to person and may change over time. Signs and symptoms can include:

• Anemia. Sickle cells break apart easily and die. Red blood cells usually live for about 120 days before they need to be replaced. But sickle cells typically die in 10 to 20 days, leaving a shortage of red blood cells (anemia). Without enough red blood cells, the body can't get enough oxygen and this causes fatigue.

• Episodes of pain. Periodic episodes of extreme pain, called pain 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.

  The pain varies in intensity and can last for a few hours to a few days. Some people have only a few pain crises a year. Others have a dozen or more a year. A severe pain crisis requires a hospital stay.

  Some adolescents and adults with sickle cell anemia also have chronic pain, which can result from bone and joint damage, ulcers, and other causes.

• Swelling of hands and feet. The swelling is caused by sickle-shaped red blood cells blocking blood circulation in the hands and feet.
• Frequent infections. Sickle cells can damage the spleen, increasing vulnerability to infections. Infants and children with sickle cell anemia commonly receive vaccinations and antibiotics to prevent potentially life-threatening infections, such as pneumonia.
• Delayed growth or puberty. Red blood cells provide the body with the oxygen and nutrients needed for growth. A shortage of healthy red blood cells can slow growth in infants and children and delay puberty in teenagers.
• Vision problems. Tiny blood vessels that supply the eyes can become plugged with sickle cells. This can damage the retina — the portion of the eye that processes visual images — and lead to vision problems.

When to see a doctor

See your health care provider right away if you or your child has symptoms of sickle cell anemia. Because children with sickle cell anemia are prone to infections, which often start with a fever and can be life-threatening, seek prompt medical attention for a fever greater than 101.5 F (38.5 C).

Seek emergency care for symptoms of stroke, which include:

• One-sided paralysis or weakness in the face, arms or legs
• Confusion
• Difficulty walking or talking
• Sudden vision changes
• Unexplained numbness
• Severe headache

Causes

Sickle cell anemia is caused by a change in the gene that tells the body to make the iron-rich compound in red blood cells called hemoglobin. Hemoglobin enables red blood cells to carry oxygen from the lungs throughout the body. The hemoglobin associated with sickle cell anemia causes red blood cells to become rigid, sticky and misshapen.

For a child to be affected, both mother and father must carry one copy of the sickle cell gene — also known as sickle cell trait — and pass both copies of the altered form to the child.

If only one parent passes the sickle cell gene to the child, that child will have the sickle cell trait. With one typical hemoglobin gene and one altered form of the gene, people with the sickle cell trait make both typical hemoglobin and sickle cell hemoglobin.

Their blood might contain some sickle cells, but they generally don't have symptoms. They're carriers of the disease, however, which means they can pass the gene to their children.

Risk factors

For a baby to be born with sickle cell anemia, both parents must carry a sickle cell gene. In the United States, sickle cell anemia most commonly affects people of African, Mediterranean and Middle Eastern descent.

Complications

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

• Stroke. Sickle cells can block blood flow to an area of the brain. Signs of stroke include seizures, weakness or numbness of the arms and legs, sudden speech difficulties, and loss of consciousness. If your child has any of these signs and symptoms, seek medical treatment immediately. A stroke can be fatal.
• Acute chest syndrome. A lung infection or sickle cells blocking blood vessels in the lungs can cause this life-threatening complication, resulting in chest pain, fever and difficulty breathing. It might require emergency medical treatment.
• Pulmonary hypertension. People with sickle cell anemia can develop high blood pressure in their lungs. This complication usually affects adults. Shortness of breath and fatigue are common symptoms of this condition, which can be fatal.
• Organ damage. Sickle cells that block blood flow to organs deprive the affected organs of blood and oxygen. In sickle cell anemia, blood is also chronically low in oxygen. This lack of oxygen-rich blood can damage nerves and organs, including kidneys, liver and spleen, and can be fatal.
• Splenic sequestration. A large number of sickle cells can get trapped in the spleen, causing it to enlarge and possibly causing belly pain on the left side of the body. This can be life-threatening. Parents of children with sickle cell anemia should learn to regularly feel their child's spleen for enlargement.
• Blindness. Sickle cells can block tiny blood vessels that supply the eyes. Over time, this can lead to blindness.
• Leg ulcers. Sickle cell anemia can cause painful open sores on the legs.
• Gallstones. The breakdown of red blood cells produces a substance called bilirubin. A high level of bilirubin in the body can lead to gallstones.
• Priapism. In this condition, men with sickle cell anemia can have painful, long-lasting erections. Sickle cells can block the blood vessels in the penis, which can lead to impotence over time.
• Deep vein thrombosis. Sickling of red cells can cause blood clots, increasing the risk of a clot lodging in a deep vein (deep vein thrombosis) or a lung (pulmonary embolism). Either can cause serious illness or even death.
• Pregnancy complications. Sickle cell anemia can increase the risk of high blood pressure and blood clots during pregnancy. It can also increase the risk of miscarriage, premature birth and having low birth weight babies.

Prevention

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

Diagnosis

A blood test can check for the form of hemoglobin that underlies sickle cell anemia. In the United States, this blood test is part of routine newborn screening. 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 the sickle cell form of hemoglobin.

If you or your child has sickle cell anemia, your doctor might suggest other tests to check for possible complications of the disease.

If you or your child carries the sickle cell gene, you'll likely be referred to a genetic counselor.

Assessing stroke risk

A special ultrasound machine can reveal which children have a higher risk of stroke. This painless test, which uses sound waves to measure blood flow in the brain, can be used in children as young as 2 years. Regular blood transfusions can decrease stroke risk.

Tests to detect sickle cell genes before birth

Sickle cell disease can be diagnosed in an unborn baby by sampling some of the fluid surrounding the baby in the mother's womb (amniotic fluid). If you or your partner has sickle cell anemia or the sickle cell trait, ask your doctor about this screening.

Treatment

Management of sickle cell anemia is usually aimed at avoiding pain episodes, relieving symptoms and preventing complications. Treatments might include medications and blood transfusions. For some children and teenagers, a stem cell transplant might cure the disease.

Medications

• Hydroxyurea (Droxia, Hydrea, Siklos). Daily hydroxyurea reduces the frequency of painful crises and might reduce the need for blood transfusions and hospitalizations. But it can increase the risk of infections. Don't take the drug if you're pregnant.
• L-glutamine oral powder (Endari). The FDA recently approved this drug for treatment of sickle cell anemia. It helps in reducing the frequency of pain crises.
• Crizanlizumab (Adakveo). This drug, given by injection, can help reduce the frequency of pain crises in adults and children older than 16. Side effects can include nausea, joint pain, back pain and fever.
• Voxelotor (Oxbryta). This drug is used to treat sickle cell disease in adults and children older than 12. Taken orally, this drug can lower the risk of anemia and improve blood flow throughout the body. Side effects can include headache, nausea, diarrhea, fatigue, rash and fever.
• Pain-relieving medications. Your doctor might prescribe narcotics to help relieve pain during sickle cell pain crises.

Preventing infections

Children with sickle cell anemia might receive penicillin between the ages of about 2 months old until at least age 5 years. Doing so helps prevent infections, such as pneumonia, which can be life-threatening to children with sickle cell anemia.

Adults who have sickle cell anemia might need to take penicillin throughout their lives if they've had pneumonia or surgery to remove the spleen.

Childhood vaccinations are important for preventing disease in all children. They're even more important for children with sickle cell anemia because their infections can be severe.

Your child's doctor should ensure that your child receives all the recommended childhood vaccinations, as well as vaccines against pneumonia, meningitis, hepatitis B and an annual flu shot. Vaccines are also important for adults with sickle cell anemia.

During the COVID 19 pandemic, people with sickle cell anemia should take extra precautions, such as staying isolated at home as much as possible and for those who are eligible, getting vaccinated.

Surgical and other procedures

• Blood transfusions. These are used to treat and prevent complications, such as stroke, in people with sickle cell disease.

  In a red blood cell transfusion, red blood cells are removed from a supply of donated blood, then given through a vein to a person with sickle cell anemia. This increases the number of normal red blood cells, which helps reduce symptoms and complications.

  Risks include an immune response to the donor blood, which can make it hard to find future donors; infection; and excess iron buildup in your body. Because excess iron can damage your heart, liver and other organs, you might need treatment to reduce iron levels if you undergo regular transfusions.

• Stem cell transplant. Also known as bone marrow transplant, this procedure involves replacing bone marrow affected by sickle cell anemia with healthy bone marrow from a donor. The procedure usually uses a matched donor, such as a sibling, who doesn't have sickle cell anemia.

  Because of the risks associated with a bone marrow transplant, including death, the procedure is recommended only for people, usually children, who have significant symptoms and complications of sickle cell anemia. A stem cell transplant is the only known cure for sickle cell anemia.

  Clinical trials are ongoing to address stem cell transplantation in adults and gene therapies.

Lifestyle and home remedies

Taking the following steps to stay healthy might help you avoid complications of sickle cell anemia:

• Take folic acid supplements daily and choose a healthy diet. Bone marrow needs folic acid and other vitamins to make new red blood cells. Ask your doctor about a folic acid supplement and other vitamins. Eat a variety of colorful fruits and vegetables, as well as whole grains.
• Drink plenty of water. Dehydration can increase your risk of a sickle cell crisis. Drink water throughout your day, aiming for about eight glasses a day. Increase the amount of water you drink if you exercise or spend time in a hot, dry climate.
• Avoid temperature extremes. Exposure to extreme heat or cold can increase your risk of a sickle cell crisis.
• Exercise regularly, but don't overdo it. Talk with your doctor about how much exercise is right for you.
• Use nonprescription medications with caution. Use pain medications, such as ibuprofen (Advil, Motrin IB, Children's Motrin, others) or naproxen sodium (Aleve), sparingly, if at all, because of the possible effect on your kidneys. Ask your doctor before taking nonprescription drugs.
• Don't smoke. Smoking increases your risk of pain crises.

Coping and support

If you or someone in your family has sickle cell anemia, you might consider the following to help you cope:

• Finding someone to talk with. Living with a chronic illness is stressful. Consider consulting a mental health professional, such as a psychologist, counselor or social worker, to help you cope.
• Join a support group. Ask your health care provider about support groups for families in your area. Talking with others who are facing challenges similar to yours can be helpful.
• Exploring ways to cope with the pain. Work with your health care provider to find ways to control your pain. Pain medications can't always take all the pain away. Different techniques work for different people, but it might be worth trying heating pads, hot baths, massages or physical therapy.
• Learning about sickle cell anemia to make informed decisions about care. If you have a child with sickle cell anemia, learn as much as you can about the disease. Ask questions during your child's appointments. Ask your health care team to recommend good sources of information.

Preparing for an appointment

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. He or she will likely refer you to a doctor who specializes in blood disorders (hematologist) or a pediatric hematologist.

Here's information to help you get ready for your appointment.

What you can do

Make a list of:

• Your symptoms, including any that seem unrelated to the reason for which you scheduled the appointment, and when they began
• Key personal information, including family medical history and whether anyone has sickle cell anemia or has the trait for it
• Questions to ask your doctor

Bring a family member or friend along, if possible, to help you remember the information you're given.

For sickle cell anemia, questions to ask your health care provider include:

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

Don't hesitate to ask other questions.

What to expect from your doctor

Your doctor is likely to ask you questions, including:

• When did you notice your child's symptoms?
• Have they been continuous or occasional?
• What, if anything, seems to improve symptoms?
• What, if anything, seems to worsen them?

Copyright © 1998-2024 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved.